Learning Genetics and Evolution through scientific practices. A case study with secondary students

TESE DE DOUTORAMENTO LEARNING GENETICS AND EVOLUTION THROUGH SCIENTIFIC PRACTICES. A CASE STUDY WITH SECONDARY STUDENTS Noa Ageitos Prego ESCUELA DE DOUTORAMENTO INTERNACIONAL PROGRAMA DE DOUTORAMENTO EN EDUCACIÓN SANTIAGO DE COMPOSTELA 2019 DECLARACIÓN DA AUTORA DA TESE Learning genetics and evolution through scientific practices. A case study with secondary students Dna. Noa Ageitos Prego Presento a miña tese, seguindo o procedemento axeitado ao Regulamento, e declaro que: 1) A tese abarca os resultados da elaboración do meu traballo. 2) De selo caso, na tese faise referencia ás colaboracións que tivo este traballo. 3) A tese é a versión definitiva presentada para a súa defensa e coincide coa versión enviada en formato electrónico. 4) Confirmo que a tese non incorre en ningún tipo de plaxio doutros autores nin de traballos presentados por min para a obtención doutros títulos. En Santiago, 10 de outubro de 2019. Asdo. Noa Ageitos Prego 5 AUTORIZACIÓN DA DIRECTORA E TITORA DA TESE Learning Genetics and Evolution through scientific practices. A case study with secondary students Dna. Blanca Puig INFORMA: Que a presente tese, correspóndese co traballo realizado por Dna. Noa Ageitos Prego, baixo a miña dirección, e autorizo a súa presentación, considerando que reúne os requisitos esixidos no Regulamento de Estudos de Doutoramento da USC, e que como directora desta non incorre nas causas de abstención establecidas na Lei 40/2015. De acordo co artigo 41 do Regulamento de Estudos de Doutoramento, declara tamén que a presente tese de doutoramento é idónea para ser defendida en base á modalidade de COMPENDIO DE PUBLICACIÓNS, nos que a participación do/a doutorando/a foi decisiva para a súa elaboración. A utilización destes artigos nesta memoria, está en coñecemento dos coautores, tanto doutores como non doutores. Ademais, estes últimos teñen coñecemento de que ningún dos traballos aquí reunidos poderá ser presentado en ningunha outra tese de doutoramento. En Santiago de Compostela, 10 de outubro de 2019 Asdo. Blanca Puig Mauriz 7 AGRADECEMENTOS A realización desta tese foi posible grazas ao apoio de diversas persoas a institucións. A continuación tratarei de expresar o meu agradecemento a todas elas. En primeiro lugar, expreso o meu agradecemento ao Ministerio de Educación, Cultura y Deporte, grazas ao cal participei nos proxectos EDU2012-38022-C02-01 e EDU2015-66643-C2-2-P. Á Consellería de Cultura, Educación e Ordenación Universitaria da Xunta de Galicia, coas axudas ao Grupo de Referencia Competitiva RODA CN2012/054 e ED431C 2017/026. Á axuda de mobilidade ESERA Travel Award 2016, que me permitiu realizar unha estancia na University of Aberdeen para poder optar a mención internacional nesta tese. Á miña directora de tese, Blanca Puig. Sen a súa axuda, acompañamento, paciencia e dedicación este proxecto non tería sido posible. Graciñas por guiarme, apoiarme e ensinarme tanto ao longo destes anos. A Marilar Jiménez Aleixandre, por axudarme a comezar no mundo da investigación dirixindo o meu TFM e apoiándome e animándome nos primeiros pasos da miña formación como investigadora. A tese se desenvolveu no marco do proxecto FEDER/Ministerio de Ciencia, Innovación e Universidades – Axencia Estatal de Investigación/ Proxecto ESPIGA ("Promoviendo el Desarrollo del Pensamiento Crítico y de las dimensiones de Implicación Cognitiva y Emocional de los desempeños Epistémicos en las Clases de Ciencias en la Era de la Posverdad"), referencia PGC2018-096581-B-C22. NOA AGEITOS PREGO 8 Aos titores das escolas de verán de NARST e ESERA, pola súa axuda bos consellos nas primeiras etapas deste traballo. A Laura Colucci-Gray, por acollerme tan xenerosamente na University of Aberdeen e aportar tanto na miña formación e a esta tese. Ao alumnado e ás familias, que aceptaron formar parte neste estudo. Ao profesorado que me permitiu acompañalos nas súas aulas, en especial a Xusto Calvo, que durante dous anos me permitiu aprender da súa experiencia. Ás miñas amigas, en especial a Lucía, Cris, Thais, Fátima e Cris. Por acompañarme durante estes anos, porque unha conversa con vos é suficiente para superar os momentos de desánimo. Con moito agarimo, á miña familia. Á miña nai Carmen, polo seu apoio incondicional en todas as etapas da miña vida. Ao meu pai Xulio, quen me contaxiou o amor polo ensino, pola natureza e por aprender. Por último, a todas as mestras e profesoras coas que desfrutei aprendendo durante o colexio e o instituto, e que me motivaron para querer ser docente. Aos membros do departamento de Didácticas Aplicadas, en especial aos compañeiros da área Ciencias Experimentais. Tamén aos meus compañeiros de despacho, Sabela, Pablo, Borja e Inés, agardo poder seguir aprendendo de vós. A Ángel Carracedo, por aconsellarnos e orientarnos á hora de escoller as doenzas a traballar na aula co alumnado. 9 PRESENTATION This thesis is structured following the guidelines and regulations established for the publication of theses as a compendium of research articles. This was approved by the resolution 12 de julio de 2017 por la que se publica el Reglamento de estudios de doctorado by means of which the Regulation on PhD studies was published, and which was approved in the Pleno ordinario del Consejo de Gobierno de 12 de junio de 2017, regulated by the Real Decreto 99/201. In accordance with the regulations governing the format for the presentation of theses as a compendium of publications, we have structured the thesis in the following manner: Section 1: Introduction Section 2: Publications Section 3: Discussion Section 4: Conclusions and educational implications Section 5: References This thesis contains three original articles framed within the same line of research; the study of scientific and reasoning practices by secondary school students when learning genetics and evolution. The three articles are presented in the original language and format in which they were originally published. In addition, a fourth article is included, since it presents the design of the teaching sequence that involves the tasks object of analysis in this thesis. 1. Puig, B., Ageitos, N. & Jiménez-Aleixandre, M. P. (2017). Learning Gene Expression Through Modelling and Argumentation. A Case Study Exploring the Connections Between the Worlds of NOA AGEITOS PREGO 16 argumentación (e.g., Berland e Reiser, 2009; Passmore e Svoboda, 2012). Existe un aumento de interese na investigación sobre prácticas científicas na análise conxunta das prácticas de argumentación e modelización (e.g., Clark, Sengupta, Brady, Martinez-Garza, e Killingsworth, 2015; Passmore e Svoboda, 2012). Esta tese pretende investigar que operacións teñen lugar no desempeño de ambas prácticas científicas e as súas posibles interaccións. A retórica e argumentación e as súas interseccións no discurso A argumentación pode ser incluída dentro das prácticas epistémicas e científicas, máis tamén dentro das prácticas de razoamento. Dentro destas, autores como Martins, Mortimer, Osborne, Tsatsarelis, e Jiménez-Aleixandre (2001) propoñen explorar un conxunto máis amplo de estratexias discursivas, alén da argumentación científica, como pode ser a retórica. Son escasas as investigacións que se centran en analizar a retórica na aprendizaxe de ciencias polo alumnado, a diferenza dos estudos que abordan a argumentación (Osborne, 2001). En consecuencia, pouco se coñece sobre o papel da retórica na construción de argumentos e na aplicación do coñecementos. En liña con Osborne (2001), esta tese propón a análise da retórica como vía para lograr unha mellor comprensión sobre como promover a argumentación científica en articulación coa aplicación do coñecemento na aula de ciencias. Esta tese parte da visión de que a argumentación é unha práctica social na que os membros da comunidade procuran explicar os fenómenos estudados avaliando, criticando e revisando as conclusións a través do discurso (Berland e Reiser, 2011). Vemos a retórica como unha compoñente vital da linguaxe, así como unha ferramenta para comprender o discurso científico. O termo retórica pode ser empregado para referirse á articulación de diferentes modos de comunicación, como linguaxe, imaxes e xestos, para producir textos coherentes, que axudan a dar forma a unha visión determinada do mundo (Driver, Newton e Osborne, 2000). Os estudos sobre a linguaxe fixeron fincapé Resumo 17 sobra as interseccións entre a argumentación e a retórica como prácticas discursivas que poden dar forma ao pensamento dos estudantes e a outras actividades epistémicas (Kelly e Bazerman, 2003). Aprendizaxe de xenética e evolución. Principais dificultades Durante as últimas décadas, producíronse grandes avances conceptuais e tecnolóxicos no campo da xenética, moitos dos cales chegan ao ámbito público. Todo isto require a comprensión de ideas científicas sobre xenética por parte da cidadanía (Feinstein, Allen e Jenkins, 2013; Ryder 2001). A alfabetización en xenética implica ser capaz de comprender, utilizar ou responder a información sobre fenómenos xenéticos e tecnoloxías que un individuo pode atopar en situacións da vida cotiá (Duncan, Rogat e Yarden, 2009). É dicir, tomar decisións informadas sobre cuestións sociais e científicas complexas (Shea e Duncan, 2015). A xenética é unha disciplina que presenta dificultades á hora de ensinar e aprender. Knippels (2002) agrupa en cinco categorías as dificultades atopadas na aprendizaxe de xenética: 1) vocabulario e terminoloxía específica; 2) contido matemático nas tarefas de xenética mendeliana; 3) procesos citolóxicos; 4) natureza abstracta da xenética; 5) complexidade da xenética: os problemas macro-micro. Ademais, autores como Mills Shaw, Van Horne, Zhang e Boughman (2008), fan referencia a dificultades específicas relacionadas con: a) tecnoloxías xenéticas; b) determinismo xenético; c) patróns de herdanza; d) natureza dos xenes e do material xenético; e) base xenética das enfermidades; f) investigación en xenética; g) tecnoloxías reprodutivas. En resposta a estas dificultades, xorden iniciativas docentes e propostas para superalas, sendo a unidade didáctica desta tese un exemplo que toma en conta no seu deseño aportes previos da literatura. En concreto, propostas orientadas a mellorar a comprensión do modelo de expresión dos xenes e as relacións fenotipo e xenotipo. En liña con Reinagel e Bray Speth (2016), proponse a modelización como unha práctica que axuda a mellorar a comprensión sobre a relación entre os xenes e os fenotipos. NOA AGEITOS PREGO 18 A evolución é un dos conceptos fundamentais da bioloxía, mais a súa ensinanza e aprendizaxe presenta desafíos (Andrews et al., 2017). Existen numerosos estudos que amosan ideas alternativas sobre a teoría da evolución (Alberts e Labov 2004; Ferrari e Chi, 1998; Miller, Scott e Okamoto, 2006). De acordo a Alters e Nelson (2002) estas ideas poden clasificarse segundo a súa orixe en: a) ideas que xorden de experiencias cotiás; b) ideas construídas polo propio alumnado, nas que estes acomodan nova información ao seu marco anterior; c) ideas ensinadas informalmente por outras persoas ou aprendidas na ficción; d) ideas vernáculas, que xorden da diferenza entre a definición científica dunha palabra e o seu uso cotián; e) conceptos erróneos e relixiosos. Existen escasas investigacións que aborden conxuntamente a aprendizaxe de xenética e evolución. Un dos traballos que toma como referencia esta tese é o de Kalinowski, Leonard e Andrews (2010), que mostra dificultades por parte do alumnado universitario para usar conceptos de xenética molecular á hora de construír explicacións de evolución. Isto contrasta coa idea de que a evolución para ser comprendida precisa de conceptos de paleontoloxía, embrioloxía, bioxeografía, bioloxía molecular e xenética de poboacións (Mayr, 2002). Isto leva a que cada vez exista maior consenso sobre a necesidade de potenciar os vínculos interdisciplinarios en todas estas áreas para promover a comprensión e aprendizaxe dos estudantes (Tibell e Harms, 2017). Xenética e evolución articúlanse nesta tese no contexto de relacionar dúas doenzas humanas, unha delas con compoñente xenética. Metodoloxía Esta tese forma parte da investigación cualitativa, a cal intenta investigar como as persoas constrúen o mundo ao seu redor, que fan ou que lles ocorre, tratando de obter unha visión significativa e rica da observación da situación. En concreto, enmárcase dentro dos estudos de caso que se relacionan con fenómenos sociais e poñen o foco de Resumo 19 atención nunha ou varias das súas manifestacións e no seu entorno (Swanborn, 2010). Esta tese aborda un estudo de caso único (Yin, 2003) de tipo exploratorio, no que se analizan os desempeños de prácticas científicas por un grupo de vinte estudantes en diversas tarefas que forman parte dunha unidade didáctica de xenética e evolución. O contexto no que se desenvolve o estudo é un instituto de ensino secundario (IES) do interior de Galicia. O centro, malia situarse nunha vila, considérase semiurbano e recibe alumnado do centro da vila e de diversas aldeas que se atopan preto. O nivel socio-cultural é medio e gran parte do alumnado continúa os estudos de bacharelato ao rematar o Ensino Secundario Obrigatorio (ESO). A elección do centro participante estivo motivada polo interese do profesorado en participar no proxecto de investigación. Os participantes son dúas aulas de 20 estudantes de entre 15 e 16 anos de 4º ESO e os seus dous profesores (T1 e T2) da materia de bioloxía e xeoloxía. As dúas aulas reuníronse e o alumnado traballou como un soa aula. Ambos docentes levaban máis de 10 anos no ensino público e varios anos ensinando neste mesmo centro. No caso de T1, cabe mencionar, que participou previamente nunha investigación de didáctica de ciencias centrada no desenvolvemento da modelización en xeoloxía. Ademais, este docente elabora os seus propios modelos para traballar con eles na aula. Os dous profesores discutiron en previas reunións coas investigadoras a posta en práctica das tarefas, o deseño e adecuación destas, valorando a súa idoneidade tendo en conta as necesidades dos participantes. Estas reunións realizáronse tanto no centro educativo como no centro de traballo da investigadora. Cómpre sinalar que ambos docentes desenvolveron as tarefas na aula, mais o seu rol foi distinto. T1 dirixía as sesións e guiaba aos distintos grupos no desenvolvemento das actividades e T2 apoiaba a T1 no desenvolvemento das actividades Ambos docentes respondían as demandas dos distintos grupos e proporcionaban a andamiaxe que demandaba cada grupo. NOA AGEITOS PREGO 20 As actividades obxecto de análise nesta tese forman parte dunha primeira secuencia didáctica sobre xenética e evolución e prácticas científicas. En concreto analízanse a primeira e última tarefas grupais. O deseño das actividades tivo en conta os contidos relacionados con xenética e evolución do currículo vixente (CCEOU, 2015), ademais dos resultados de investigacións anteriores sobre ensinanza de xenética e evolución. A secuencia aborda diversas doenzas con compoñente xenética que requiren a comprensión e aplicación do modelo de expresión dos xenes. Ademais, co fin de vencellar xenética e evolución, inclúese unha doenza que se relaciona evolutivamente cunha das enfermidades previamente traballadas. A secuencia didáctica 1 inclúe catro actividades realizadas en pequenos grupos en seis sesións. As actividades ordénase seguindo dous criterios: 1) o nivel de complexidade das enfermidades, desde unha enfermidade máis sinxela, monoxénica (a anemia falciforme) ata unha máis complexa, polixénica, como o cancro de mama; 2) a progresión no desempeño das prácticas científicas. Pártese dunha actividade na que se require elaborar un modelo “material” sobre a expresión dos xenes para explicar a anemia falciforme; continúase con dúas tarefas nas que é preciso aplicar o modelo a outras enfermidades humanas; e remátase a secuencia coa aplicación do modelo inicial elaborado para establecer as relacións evolutivas entre dúas enfermidades. A toma de datos tivo lugar no transcurso normal das distintas sesións. A investigadora, presente en seis sesións gravadas en son e vídeo tivo un papel de observadora non participante, co propósito de non influír no desenvolvemento das sesións. Decidiuse optar por catro instrumentos para a recollida de datos e triangulación: 1) enquisas aos docentes, 2) os informes escritos das tarefas, 3) as gravacións en son e vídeo, 4) as notas de campo da investigadora. O proceso de análise seguido consta de varias fases. Comézase pola transcrición das gravacións das conversas, sendo a unidade de análise a quenda. Diferentes episodios son identificados, nalgúns casos, e a Resumo 21 continuación realízase a categorización. O proceso de análise ten lugar en interacción cos datos e a literatura existente, dado que entendemos que a análise non debe partir de categorías predeterminadas (Kelly e Takao, 2002), senón que deben definirse en interacción coa literatura e os propios datos. Diversas rúbricas propostas en investigacións previas son adaptadas en interacción cos datos para abordar os diferentes obxectivos de investigación. Publicacións Publicación 1. Learning Gene Expression Through Modelling and Argumentation. A Case Study Exploring the Connections Between the Worlds of Knowledge A investigación sobre prácticas científicas na actualidade pon especial interese en estudar as relacións que teñen lugar entre prácticas como a modelización e a argumentación científica (e.g., Blanco-Anaya, Justi e Díaz de Bustamante, 2017; Passmore e Svoboda, 2012). Na investigación sobre aprendizaxe de bioloxía, resulta de especial interese analizar estas relacións entre prácticas en contextos como a aprendizaxe de como a xenética e evolución, onde o alumnado presenta dificultades (Kampourakis e Zogza, 2009; Shea, Duncan e Stephenson, 2015). A modelización pode axudar aos estudantes a comprender e argumentar sobre temas relacionados coa xenética (Reinagel e Bray Speth, 2016). Neste traballo proponse modelizar a expresión dos xenes como vía para aprender xenética molecular e identificar os procesos e entidades que participan que non son visibles, así como para explicar enfermidades cunha compoñente xenética. Este estudo está enmarcado na proposta de Tiberghien (2000) sobre os dous mundos do coñecemento, o “mundo das teorías e modelos” e o “mundo dos obxectos e eventos” que forman parte dos procesos modelización, segundo esta autora. Neste caso, amplíase o marco de Tiberghien (2000) engadíndose un terceiro mundo que se corresponde co “mundo das representacións”. Preténdese examinar como interaccionan as prácticas de modelización e argumentación, así como as conexións que establecen entre os tres mundos do coñecemento na NOA AGEITOS PREGO 22 modelización da expresión dos xenes polo alumnado. Nesta publicación abórdanse as preguntas de investigación P1 e P2 da tese. A análise do discurso permitiu identificar un repertorio de operacións de argumentación e de modelización e as conexións que establecen entre os mundos do coñecemento. A operación de modelización máis frecuente é de carácter manipulativo, sendo as relacionadas co meta-coñemento da práctica escasas neste contexto. En canto ás operacións de argumentación, o uso de probas é a predominante durante todo o proceso de modelización. Pola contra, as relacionadas coa crítica son pouco frecuentes, o que revela dificultades polo alumnado para avaliar enunciados e modelos propostos por outros. As conexións co mundo natural son as menos frecuentes, o que apunta a necesidade de prestar atención a este dominio de coñecemento na modelización. Publicación 2: Argumentation as a tool to explain the evolutionary links between human diseases: a case study Numerosos estudos foron propostos para promover a argumentación na aprendizaxe de ciencias, xa que, malia ser unha compoñente clave das prácticas de construción de coñecemento, a súa presenza nas aulas é escasa (Berland e Reiser, 2009). Existen estudos que abordan a argumentación no contexto de aprendizaxe de xenética e evolución, mais sempre abordando ambas disciplinas por separado. Este artigo examina a argumentación e argumentos escritos do alumnado nunha actividade que requiría establecer relacións explicativas entre a anemia falciforme e a malaria. Contexto que pon en relación a xenética e a evolución. Nesta publicación abórdanse as preguntas de investigación P3 e P4 da tese. A análise céntrase nos argumentos escritos construídos en grupos polo alumnado participante, tanto no que se refire á súa estrutura causal, como á súa calidade en base a coñecementos aplicados e xustificacións aportadas. Ademais, analízanse os datos empregados na elaboración de argumentos finais consensuados sobre as relacións entre as dúas doenzas. Resumo 23 Diversas rúbricas foron adaptadas da literatura en interaccións cos datos para levar a cabo esta análise. Os resultados apuntan ás dificultades dos estudantes para construír argumentos de calidade en termos de usar unha linguaxe causal clara e nocións de xenética e evolución. A maioría do alumnado utiliza os datos proporcionados na tarefa, mais parte destes datos son reformulados para acomodarse ás súas teorías previas. Representacións sociais e culturais relacionadas coa orixe da anemia falciforme así como posicións teleolóxicas son identificadas no discurso escrito. Publicación 3. Examining reasoning practices and epistemic actions to explore students’ understanding of genetics and evolution Este artigo céntrase na análise dos movementos discursivos e prácticas de razoamento no discurso oral do alumnado nunha tarefa, a mesma que na publicación 2, que require explicar as relacións entre a anemia falciforme e a malaria. Examínanse as interseccións entre a retórica e a argumentación, así como as accións epistémicas que mobilizan neste contexto. Nesta publicación abórdanse as preguntas de investigación P5 e P6 da tese. A análise dos movementos retóricos e do uso de probas permite identificar tres marcos de coñecemento nos que o alumnado se sitúa á hora de discutir as relacións entre as dúas enfermidades humanas. O tipo de accións epistémicas identificadas e nas que participa o alumnado, parecen estar directamente relacionadas co contido dos datos proporcionados, resultado que apunta á importancia destes. Ademais, as accións epistémicas parecen condicionar o nivel de sofisticación das explicacións elaboradas sobre as relacións evolutivas entre dúas enfermidades humanas. Isto relaciónase coas dificultades atopadas no emprego dunha adecuada terminoloxía sobre evolución e sobre xenética no discurso oral. Identifícanse no discurso, de igual xeito que nos argumentos escritos, representacións sociais relacionadas con diferenzas culturais e biolóxicas entre grupos humanos e posicións teleolóxicas. Discusión xeral NOA AGEITOS PREGO 24 O uso de datos como probas é un fío condutor ao longo da tese. No primeiro artigo vemos como ten un papel fundamental, sendo a operación de uso de probas a máis frecuente e a que permite unir os tres mundos de coñecemento. O rol no segundo e terceiro artigos vén dado polo deseño da propia tarefa, que require ao alumnado analizar e usar un repertorio de datos con distinto nivel epistémico para chegar a unha conclusión final sobre as relacións entre a anemia falciforme e a malaria. Neste caso, os resultados amosan que o alumnado utiliza en cada momento os datos que se lles proporcionaban, mais en ocasións acomodan estes en base ás súas teorías previas e construcións culturais e sociais. A análise dos datos do segundo e terceiro artigo apunta á existencia de ideas alternativas sobre xenética e evolución. Parte destas ideas están relacionadas con explicacións teleolóxicas, e outra parte, con representacións sociais relacionadas coa orixe da anemia falciforme en África. A análise do discurso oral permítenos comprobar que o alumnado non foi quen de construír unha explicación sofisticada sobre a relación entre a malaria e a anemia falciforme. Outro elemento en común que emerxe da análise dos tres artigos ten que ver coas dificultades do alumnado para moverse entre distintos niveis de organización biolóxica (moleculares, celulares e individuais), o que está en coherencia con investigacións previas (por exemplo, Marbach-Ad e Stavy, 2000; van Mil Boerwinkel e Waarlo, 2013). Na primeira tarefa, analizada no artigo 1, os materiais proporcionados no kit pretendían servir para facilitar a identificación de entidades de distintos niveis de organización biolóxica (molecular e celular). A tarefa abordada nas publicacións 2 e 3, relativa ás relacións evolutivas entre dúas enfermidades, presentaba datos destes niveis pero tamén o nivel de poboación. Os estudantes tiveron dificultades á hora de discutir en profundidade os datos de diferentes niveis presentados que poderían axudar a construír unha explicación evolutiva. Conclusións A análise do obxectivo 1, examinar as interaccións entre a modelización e a argumentación e as súas conexións cos tres mundos Resumo 25 do coñecemento no contexto de aprendizaxe da expresión dos xenes en alumnado de secundaria, permítenos establecer cinco conclusións: 1. Identifícanse unha serie de operacións argumentativas e de modelización durante a modelización a expresión dos xenes por parte do alumnado no contexto de explicar unha enfermidade humana. 2. O "uso de probas" foi unha operación central no proceso de modelización da expresión dos xenes, que permitiu conectar os tres mundos do coñecemento (teorías e mundo natural; teorías e representacións; e representacións e mundo natural). 3. Examinar a modelización permite identificar as conexións entre os tres mundos do coñecemento relacionados coa expresión dos xenes que establecía alumnado. O mundo natural foi o menos frecuente na modelización da expresión dos xenes. 4. Parece que existe unha relación entre a sofisticación das representacións, as conexións entre os mundos do coñecemento e as interaccións entre argumentación e modelización. Un maior número de conexións produciuse cando se estableceron máis interaccións, o que resultou nunha representación máis sofisticada. 5. A crítica foi unha operación difícil de realizar polo alumnado mentres se dedicaban á construción do modelo, dando explicacións deterministas. A análise do obxectivo 2, examinar os argumentos e datos empregados polo alumnado de secundaria para explicar as relacións entre dúas enfermidades humanas na aprendizaxe de xenética e evolución, permítenos establecer dúas conclusións: 6. Foron escasas as consideracións de xenética e evolución na maioría dos argumentos finais escritos consensuados polo alumnado sobre as relacións entre a anemia falciforme e a malaria. 1. INTRODUCTION 1.1 JUSTIFICATION OF THE RESEARCH This doctoral thesis focuses on investigating secondary students’ performance of argumentation and modelling, as well as the reasoning practices and epistemic actions enacted when learning genetics and evolution. The publications included in this thesis as a compendium of articles address, on the one hand, the study of argumentation and modelling practices and their mutual interactions in relation to the worlds of knowledge that are put into play when modelling gene expression. On the other hand, they introduce rhetoric into the analysis of argumentation and examine the use of evidence and the epistemic actions performed by students in the context of learning together genetics and evolution. The main reason for addressing this research project is related to personal and professional concerns of the researcher, a secondary school science teacher who has noticed that secondary students show difficulties for learning genetics and evolution. Another motivating factor was the need to connect both domains, evolution and genetics, using significant contexts, such as those addressed in this thesis. This concern is aligned with the existence of a large body of research regarding genetics education, which reveals students' difficulties both in understanding and in applying the model of gene expression. Moreover, in the case of evolution, the identification of teleological positions in the literature (e.g., Kampourakis & Zogza, 2009; Puig & Jiménez-Aleixandre, 2010) understanding this theory in terms of purpose or a tendency towards improvement is another reason for addressing this research. Genetics research is progressing with new data and new techniques (Shea, Duncan & Stephenson, 2015) as well as new concepts and new terms (Brown, 2008; Flodin, 2017). Scientific advances in the field such NOA AGEITOS PREGO 34 as gene therapy, genotyping tests and the use of stem cells require decision-making and a critical literacy from citizens. Regarding evolution, according to Dobzhansky (1973) nothing in biology makes sense except in the light of evolution. Evolution continues to operate nowadays, something that students do not always identify (Puig, 2013). For instance, it can be associated with the presence of human diseases, being particularly clear in the case of the relationships between malaria and sickle cell disease (hereinafter SCD) addressed in this thesis. Current research into genetics and evolution education suggests that these two domains could be connected in order to improve their understanding. Previous studies point to the benefits of teaching genetics before evolution because it improves students’ understanding (Mead, Hejmadi & Hurst, 2017). It has also been suggested that specific emphasis on genetics during instruction may enhance conceptual change in evolution (Kampourakis & Zogza, 2009). There is scarce evidence regarding the benefits of genetics and evolution instruction through students' engagement in scientific practices, being this one of the main contributions of the thesis. This research also contributes to two personal objectives. On the one hand, as a teacher, it contributes to the search for innovative teaching methodologies that facilitate learning about genetics and evolution through scientific practices in the secondary school classroom. On the other hand, as a researcher, it seeks to contribute to the study of the origin and possible causes of students’ learning difficulties in both domains through the analysis of scientific practices and rhetoric. The development of resources and teaching materials for the instruction of gene expression and its application to diverse contexts related to human diseases is also a goal of this thesis. Furthermore, these motivations are connected to the science education research developed within the research group RODA (Reasoning, Discourse and Argumentation) at the University of Santiago de Compostela (USC). The investigation focuses on investigating the processes of students’ participation in the scientific practices of production, evaluation and communication of knowledge Section 1. Introduction 35 in different contexts and educational levels. In the case of this thesis, secondary education is addressed since it is the educational level in which genetics and evolution are included in the curriculum (CCEOU1, 2015). In addition, the articles of the thesis were developed within the framework of two national projects. Publications 1, 2 and 4 are related to the project "Scientific Practices in Science Teaching and Learning, Dimensions in Transference and Performance" (SCI-PRAC), code EDU2015-66643-C2-2-P. In particular, with two project objectives related to designing materials that promote argumentation, its articulation with modelling practices and with the analysis of the performance of these two practices in the science classroom. Publication 3 has been developed within the framework of this project and it was completed in a second project that recently began in 2019, "Promoting the development of critical thinking and the social and metacognitive dimension of epistemic performances in science classrooms in the post-truth era" (ESPIGA) code PGC2018-096581-B- C22. The connection with this second project is with one objective dealing with the analysis of the cognitive domain in students’ performance of epistemic practices. The thesis draws from a previous research developed within the RODA group about the use of evidence and argumentation in learning genetics in secondary education (Puig, 2013). This study revealed the existence of deterministic positions among secondary students in relation to the model of gene expression. This thesis suggests the incorporation of modelling gene expression to improve its understanding, as well as helping to overcome deterministic positions. Modelling has been proposed as a way of understanding biological processes that are not visible (Venville & Donovan, 2008). We believe that this practice is a suitable starting context for genetics learning, given the variety of elements and processes at the cellular and molecular level that are difficult to visualise (Freidenreich, Duncan & Shea, 2001). In addition, the thesis follows Shea, Duncan & Stephenson’s proposal 1 CCEOU: Regional Council of Culture, Education and University NOA AGEITOS PREGO 36 (2015) that supports beginning the instruction with molecular genetics, using modelling as a way of learning molecular processes which are involved in gene expression, before transferring this knowledge to the construction of arguments about Mendelian genetics. Considering the current Spanish curriculum (CCEOU, 2015), the context of genetics is used as a starting point before moving towards learning about evolution, which has shown to increase the students' understanding of evolution (Mead, Hejmadi & Hurst, 2017). To this end, it was decided that the sequence would end by addressing together evolution and genetics in order to favour students' effective learning of both domains. Publication 4 develops and justifies the design of the teaching sequence for this thesis, which allows to formulate the research objectives of the study. This design was developed in collaboration with the biology teachers involved and the scientific content of the activities was validated by an international expert in clinical genetics. Moreover, an analysis of the literature in genetics and evolution learning was carried out. Articles 1, 2 and 3, which addressed the objectives of the thesis, are closely linked since: 1) they all analyse scientific practices, modelling (paper 1) and argumentation; 2) they focus on the examination of the use of evidence. In the case of paper 1, attention is on the use of evidence during the process of modelling gene expression; and in the case of papers 2 and 3, the analysis focuses on the students’ use of evidence when making explanatory links between two human diseases; 3) papers 2 and 3 are based on the results obtained in the previous papers. They advance in the direction of the objectives proposed in the thesis. Publication 1 addresses the analysis of modelling and argumentation processes while students engage in modelling gene expression model to explain SCD (task 1 of the teaching sequence). The paper helps to advance in the analysis of modelling, providing a Section 1. Introduction 37 framework based on Tiberghien’s (2000) proposal regarding the worlds of knowledge. Our proposal includes a third domain or world of knowledge called the world of representations. In addition, a rubric proposed by Jiménez-Aleixandre, Puig, Bravo and Crujeiras (2014) is modified in order to identify the operations of argumentation that appear in this context. The examination of the modelling and argumentation operations allows us the identification of the interactions that occur between both practices, and the connections established among the three worlds of knowledge. This article was developed in collaboration with M. P. Jiménez-Aleixandre, an international expert in argumentation in science education research. In publication 2 the focus of analysis is on the written arguments presented by the groups when participating in a task that includes genetics and evolution contents. It is an argumentation task structured in 4 stages that involves the progressive analysis of data with a different epistemic level in order to establish connections between sickle cell disease and malaria and reach a final conclusion. On the one hand, the quality of final written arguments agreed upon in the groups is examined, and on the other hand, the use of data and its role in establishing successive arguments throughout the task is explored. The analysis reveals difficulties in the construction of arguments, both in the use of justifications and in the application of scientific terminology. In addition, teleological positions are identified. The results of this article suggest the need for oral discourse to be analysed in detail in order to better understand the processes that lead to the construction of these arguments, as well as the possible causes of the detected difficulties. Publication 3 is based on the results obtained in paper 2 and the task under analysis is the same. Rhetoric is introduced to the analysis of oral argumentation. In particular rhetorical moves (Swales, 1990) and the use of evidence in argumentation as well as the intersections between them, are analysed. This publication also includes the analysis of epistemic actions, a framework of analysis which adapted Pontecorvo & Girardet’s proposal (1993). The analysis of this paper allows the identification of frames of thinking which students are NOA AGEITOS PREGO 38 positioned in, as well as the epistemic actions performed. These results help to understand how epistemic actions related to the use of time scales and the ability to define notions can influence students when establishing complex connections in biological processes, such as the coevolution between two human diseases. It is worth noting that the analysis in this article was initiated during a three-month pre-doctoral research stay at the University of Aberdeen, partially funded by an ESERA travel Award 2016. This gave rise to the co-authorship of the third publication with Professor Laura Colucci- Gray, who contributed to the incorporation of the framework of rhetoric in research. In order to prepare this collection of thesis publications, it was necessary to prepare proposals prior to national and international conferences. In addition, the advances of the thesis were presented in two summer schools of recognised international prestige. Firstly in 2015, it was presented at the Sandra K. Abell Institute for Doctoral Students (SKAIDS), held at the University of Colorado Boulder (USA) between the 12th and 17th of July 2015; and secondly, at the Esera Summer school 2016, held at Ceske Budejovice (Czech Republic) between the 22nd and 26th of August 2016. Some posters were created at these summer schools and these were presented in specific poster sessions at both NARST 2016 and ESERA 2017. The conference papers and posters developed during the thesis are displayed below. Ageitos, N. & Puig, B. (2015). Unha proposta didáctica de modelización e argumentación científica sobre enfermidades xenéticas. Communication presented in III Encontro Mocidade Investigadora, Santiago de Compostela, Spain, 25th to 26th of March 2015. Ageitos, N. & Puig, B. (2015). Construír o modelo de expresión dos xenes para explicar enfermidades xenéticas. Communication Section 1. Introduction 39 presented in XXVIII Congreso Enciga, Sarria, Spain, 19th to 21st of November 2015. Ageitos, N. & Puig, B. (2016). La modelizacin para el aprendizaje de enfermedades genticas. El caso de la anemia falciforme. Poster in V Seminario Ibero-Americano CTS, IV Seminario CTS, Aveiro, Portugal, 4th to 6th of July 2016. Ageitos, N. & Puig, B. (2016). Students’ arguments and argumentation to explain the evolutionary links between two human diseases. Communication presented in ERIDOB, Karlstad (Sweeden), 5th to 9th of September 2016. Ageitos, N. & Puig, B. (2016). Exploring the Articulation of Scientific Practices of Modeling and Argumentation in a Sequence on Genetic Diseases. Póster presented in NARST Annual International Conference, Baltimore, EEUU, 14th to 17th of April 2016. Ageitos, N.; Puig, B. & Colucci, L. (2017). Comunication in the Simposio Prácticas de argumentación en el aula y su contribución a la competencia científica. X Congreso Internacional sobre Investigación en la Didáctica de las Ciencias, Sevilla, Spain, 5th to 8th of September 2017. Puig, B. & Ageitos, N. (2017). Interactions between Modelling and Argumentation while Building the Model of Gene Expression. Communication presented in the Symposio “Deepening Students’ Understanding of Modern Genetics: Four Approaches that Link Molecular Genetics with Mendelian Genetics”. NARST Annual International Conference, San Antonio, EEUU, 22nd to 25th of April 2017. Ageitos, N.; Colucci-Gray, L & Puig, B. (2017). Examining students' understanding of genetics through a linguistic analysis of thinking strategies. Paper presented at ESERA Conference 2017, Dublin, Ireland, 21st to 25th of August 2017. NOA AGEITOS PREGO 40 Ageitos, N. & Puig, B. (2017). Interactions between argumentation and modelling in genetics’ instruction about human diseases. Poster presented at ESERA Conference 2017, Dublin, Ireland, 21st to 25th of August 2017. Ageitos, N.; Colucci-Gray, L & Puig, B. (2018). Students' arguments and reasoning in genetics: dealing with the complex interactions between genotype and phenotype in the expression of animal diseases. Communication presented in XII Conference of European of Researchers in Didactics of Biology, Zaragoza, Spain, 2nd to 6th of July 2018. Ageitos, N. & Puig, B. (2018). Las prácticas científicas en la enseñanza sobre genética: argumentación sobre el modelo de expresión de una enfermedad animal. Communication presented in 28 Encuentros de Didáctica de las Ciencias Experimentales. A Coruña, Spain, 5th to 7th of September 2018. Ageitos, N.; Colucci-Gray, L & Puig, B. (2019). Arguing to explan the evolutionary links between two human diseases. A case study research. Communication presented in 13th International Conference for ESERA, Boloña, Italia, 26th 30th August 2019. 1.2 OBJECTIVES The main goal of this thesis is to examine the scientific and reasoning practices as well as epistemic actions performed by secondary students when learning genetics and evolution in the context of explaining human diseases. In order to address this general goal, it is necessary to explore, on the one hand, modelling and argumentation practices enacted by students and their mutual interactions in connection with the worlds of knowledge; and on the other hand, the reasoning practices and epistemic actions performed by students. This general goal is addressed through three research objectives, and their related research questions: Section 1. Introduction 41 O1. To examine how modelling and argumentation interact and connect the three worlds of knowledge in the context of learning gene expression. This is addressed through the following research questions, that paper 1examines: RQ1) What argumentative and modelling operations do students enact in the process of modelling gene expression? Specifically, which operations allow connecting the three worlds of knowledge? RQ2) What are the interactions between modelling and argumentation in modelling gene expression? To what extent do these interactions help students connect the three worlds of knowledge and modelling gene expression? O2. To examine secondary students’ arguments and the data used while developing explanatory links between two human diseases in genetics and evolution instruction. This is addressed through the following research questions, analysed in paper 2: RQ3) What is the nature of students’ arguments while explaining the evolutionary links between two human diseases? RQ4) What data do students mobilise and how do they use them to support their arguments regarding the relationships between these two diseases? O3. To examine the intersections between rhetoric and argumentation, and epistemic actions in students’ discourse in the contest of learning genetics and evolution. This is addressed through the following research questions, analysed in paper 3: RQ5) What frames of thinking emerge from the examination of students’ rhetorical moves and use of evidence when they are learning about topics in genetics and evolution? NOA AGEITOS PREGO 48 skills, skills which are required in order to tackle everyday life issues related with the rapid advances in science. This thesis focuses on the students’ capacity to build arguments supported by evidence, but also on their capacity to reflect on their own arguments and reformulate them based on the evaluation of data. Evaluation, referred to as how students challenge other student’s arguments (Jin, Hokayem, Wang & Wei, 2016) is an important variable when constructing logical arguments (Christodoulou & Osborne, 2014). From a socio-cultural perspective, rhetorical practices may be seen as ‘linguistic devices’ for the organisation and structuring of arguments. Argumentative moves can therefore be used as cues for disclosing underlying sets of rhetorical narratives, looking at how ideas of systemic interactions are visualised and addressed by students’ meaning-making strategies. Emphasis is on the rhetorical or discursive moves that shape the students’ arguments and construction of knowledge in genetics and evolution, two central domains of biology which are known to be difficult to teach and to learn (e.g. Bray Speth et al., 2014; Zohar & Nemet, 2002). Arguments are considered in this study as being comprised of the basic elements that Toulmin described in TAP model (Toulmin, 1958). The elements that are part of the argument structure are, according to Toulmin, the data to make qualified claims, warrants supported with backings that connect data with the claim and rebuttals. 1.3.3 Learning Genetics and Evolution. Difficulties and challenges Difficulties related to genetics and evolution learning have been broadly reported in the literature. However, scarce research has been carried out into the context of genetics and evolution learning, primarily addressing both disciplines together. In this line, this section addresses the most common difficulties in both domains, making links between them in the final part. Section 1. Introduction 49 1.3.3.1 Genetics learning. The model of gene expression and determinism Over the last few decades, there have been significant conceptual and technological advances in the genetics field, many of which have reached the public domain. All of these developments have required for citizens to understand scientific ideas on genetics (Feinstein, Allen & Jenkins, 2013; Ryder, 2001). Since the goal of science education is to provide citizens with scientific knowledge, the implications of current genetic and genomic technologies on our lives must be addressed in science instruction. For this reason, molecular genetics is a central part of the secondary curriculum in different parts of the world, nonetheless it is considered to be a difficult area in science teaching and learning (Bahar, Johnstone, & Hansell, 1999). In Spain, the official curriculum (MECD2, 2015) introduced genetics for the first time in 4º ESO3, within the subject of Biology and Geology, a non-compulsory subject. This means that some of the students may finish secondary school without having worked on genetics-related subjects in the science classroom. Genetic literacy implies being able to understand, use or answer information about genetic phenomena and technologies that an individual may encounter in everyday life situations (Duncan, Rogat and Yarden, 2009). This involves being able to make informed decisions on complex socio-scientific issues (Shea, Duncan & Stephenson, 2015). Research in this field indicates that the gap between scientific understanding of genetics and what is taught in school has increased in recent years. (Dougherty, Pleasants, Solow, Wong & Zhang, 2011). By the end of secondary school, students do not have the necessary 2 MECD: Spanish Ministry of Education, Culture and Sports 3 The fourth and last year of compulsory secondary education. In Spain, compulsory secondary education starts at the age of 12 and lasts four years, until students reach 16. Then, they can choose to continue with two more years of Baccalaureate (non-compulsory) until they reach the age of 18, during which they prepare for the university access examination. NOA AGEITOS PREGO 50 understanding of genetics in order to be able to make appropriate personal and social decisions (Lewis and Wood-Robinson, 2000). One of the difficulties highlighted in the literature regarding learning genetics is related to deterministic positions regarding the model of gene expression (e.g., Castéra, Clément, & Abrougui, 2008; Mills Shaw, Van Horne, Zhang and Boughman, 2008; Puig & Jiménez- Aleixandre, 2011). Determinism is a trend that supports the idea that "genes invariably determine characters, so that the outcomes are just a little, or not at all, affected by changes in the environment or by the different environments in which individuals live" (Kampourakis 2017, p. 6). Determinists attribute social and economic differences between different human groups or genders to heredity, thus considering the differences as innate distinctions. This deterministic view often appears in the media, exclusively attributing genes the causes of human behaviour or disease (Condit et al., 1998; Nelkin & Lindee, 1995). Keller (2005) found that belief in genetic determinism is related to negative racial stereotypes, prejudice, and sexism. For Nelkin and Lindee (2004), genetic determinism is not simply the result of a misunderstanding or simplification of science, but it may also be anchored in deep beliefs regarding social phenomena. An earlier thesis on argumentation and the use of evidence on the model of gene expression (Puig, 2013) highlighted the difficulties for secondary school students in identifying the environmental influence on gene expression in different contexts. Likewise, Castéra and Clement (2014) demonstrated that determinism does not only appear among students, but also among teachers in several countries. Determinism is not the only difficulty encountered when learning about genetics, given that there are others associated with the complexity of this subject, which according to Knipples (2002) are grouped into these five categories: 1) vocabulary and specific Section 1. Introduction 51 terminology; 2) mathematical content in the Mendelian genetics tasks; 3) cytological processes; 4) the abstract nature of genetics; 5) the complexity of genetics: macromicro problems. In addition, authors such as Mills Shaw et al. (2008), refer to specific difficulties related to: a) genetic technologies; b) genetic determinism; c) inheritance patterns; d) nature of genes and genetic material; e) genetic basis of diseases; f) genetic research; g) reproductive technologies. It is useful to be familiar with all of these difficulties in order to improve the teaching of genetics in secondary school, however Duncan and Reiser (2007) suggest that it could be classified into broader categories, such as these three: a) the invisibility and inaccessibility of genetic phenomena; b) the complexity of genetic phenomena involving several levels; and c) the ontological differences between the levels of genetic phenomena. In order to address these difficulties, educational initiatives and proposals have emerged. The teaching sequence designed in this thesis serves as an example, taking previous contributions into consideration. Specifically, the proposal aims to improve the understanding of the model of gene expression and the connections between phenotype and genotype. Authors such as Todd and Kenyon (2015) pointed out the importance of focusing instruction on proteins, studying how they are formed, what their functions are and how they are expressed. Reinagel and Bray Speth (2016) agreed with these authors and suggest modelling as a practice to help improve the understanding of the links between genes and genotypes. Besides, Mills Shaw et al. (2008) propose tackling the first years of instruction by analysing drawings and animations of cellular and sub-cellular processes in order to improve the conceptual understanding of cellular processes and to be able to connect the different levels of organisation. Another proposal is that of Lehrer and Schauble (2000). These authors encourage students to have the opportunity to review and construct their ideas over time in order to understand and apply concepts that do not tend to be understood until several years later. NOA AGEITOS PREGO 52 Following this trend, the Learning Progressions (LPs) have emerged, these are hypothetical models on how the learning of a domain develops over time with adequate instruction (Duncan, Choi, Castro-Faix & Cavera, 2017). According to Todd and Romine (2017) LPs have these distinctive characteristics: they focus on some ideas and/or practices; they contain upper and lower limits; they identify different levels of achievement in terms of performance and learning; and the achievements are attained through a specific curriculum, although these are not guaranteed. Finally, it should be noted that given that genetic determinism is a common difficulty among students that negatively affects, on the one hand, their understanding of genetics and, on the other hand, the performance of argumentation and decision-making practices; it must be addressed in the classroom. Dougherty (2009) believes that instruction in genetics should more accurately reflect what genes can and cannot do, stressing the complexity of heredity. 1.3.3.2 Evolution learning. Difficulties and proposals to address them Evolution is one of the fundamental concepts of biology, but it is also one of the most challenging concepts to learn (Andrews et al., 2017). University biology students and pre-service teachers (Miller, Scott & Okamoto, 2006; Alberts & Labov, 2004) show alternative ideas related to evolution. In our context there is ground-breaking work that advocates the incorporation of the teaching of evolution in primary education (Vázquez-Ben & Bugallo-Rodríguez, 2018). The authors propose an intervention model for this educational stage which is based on the results obtained in a study on the challenges perceived by international experts in evolution education (Vázquez Ben & Bugallo- Rodríguez, 2017). There are numerous studies that provide alternative ideas on the theory of evolution (Ferrari & Chi, 1998). According to Alters and Nelson (2002), these ideas can be classified according to their origin as a) ideas that arise from everyday experiences; b) ideas which are Section 1. Introduction 53 constructed by the students themselves in which they accommodate new information to their previous framework; c) ideas taught informally by other people or learned in fiction; d) vernacular ideas, that emerge from the difference between the scientific definition of a word and its everyday use; e) mistaken or religious concepts. Vernacular ideas, where metaphors are a clear example, are essential tools in science for the generation of new entities (Brown, 2008). All these alternative ideas can influence the way in which students apply molecular genetic concepts, and how they argue about the evolutionary links between two human diseases, such as malaria and SCD, which have been addressed in this thesis. Regarding the difficulties which have emerged in this research when it comes to understanding the theory of evolution, and more specifically the mechanism of natural selection, Gregory (2009) classifies them in four concepts or thematic blocks: a) the variation that exists between individuals; b) the origin of new characters in populations; c) heredity; d) adaptation. Explaining the origin of adaptations is a common difficulty among secondary school students, which, as Kampourakis (2013) indicates, is related to a teleological view of evolution. According to this author, teleological explanations are those in which a phenomenon is explained in terms of a final objective which it contributes to (Walsh, 2008), and which are closely related to the term "lamarckism" because they are related to Lamarck's evolution theory. In order to move beyond these teleological explanations and promote conceptual change, authors such as Kampourakis & Zogza (2009) propose replacing the old explanations with a new conceptual framework, one which is more efficient and more scientifically consistent with current theories. In this context, in addition to creating teleological explanations, students also elaborate anthropomorphic explanations and do not acknowledge the need to include causal or mechanistic reasoning when asked to articulate an explanation of biological change (Abrams & Southerland, 2001; Southerland, Abrams, Cummins & Anzelmo, 2001). NOA AGEITOS PREGO 54 As with genetics, the complexity of the subject matter associated with random evolutionary processes can also cause problem for students (Garvin-Doxas & Klymkowsky, 2008; Mead & Scott, 2010). In many cases, students are not able to recognise random processes as responsible for biological traits (Garvin-Doxas & Klymkowsky, 2008). However, it is necessary to point out that randomness in biology is not exclusive to evolution, but these phenomena are also required in order to be able to explain genetic processes such as gene expression. Nehm & Ha (2010) have shown that students find it difficult to deal with questions about evolution between species or regarding the disappearance of characteristics in populations. Little research has been carried out dealing with evolution and genetics learning together. One of the works that this thesis has taken as a reference is that of Kalinowski, Leonard and Andrews (2010), who have outlined the difficulties faced by university students in using concepts of molecular genetics when constructing explanations of evolution. Only a small proportion of the students (19%) made explicit reference to the molecular and genetic causes of variation in their explanations of evolution, focusing on mechanisms that operate at the level of organisms (Bray Speth, Long, Pennock & Ebert-May, 2009). This is in contrast with the idea that evolution needs concepts such as palaeontology, embryology, biogeography, molecular biology and population genetics in order to be understood (Mayr, 2002), leading therefore to a growing consensus on the need for the interdisciplinary connections in all these areas to be strengthened in order to promote student understanding and learning (Tibell & Harms, 2017). This thesis supports the idea that placing greater emphasis on genetics during instruction can improve conceptual change in evolution (Kampourakis & Zogza, 2009). An example of this is focusing on DNA sequences during the teaching of natural selection (Kalinowski, Leonard & Andrews, 2010). Similarly, a proposal has been made to make more connections with students' prior knowledge of genetics and evolution in order to try to gain a better understanding of the mechanism of natural selection. Furthermore, following Ferrari and Chi (1998), the Section 1. Introduction 55 aim is for students to understand the multiple levels of organisation of living organisms, as well as the different temporal and spatial scales on which evolution operates. Genetics and evolution are articulated in this thesis in the context of relating two human diseases, one of them with a genetic component. 1.4 METHODOLOGY The thesis is framed within qualitative research which focused on the processes of knowledge construction and epistemic performances by secondary students in science classrooms. A longitudinal case study was carried out with a group of students from grade 10 (4º ESO) during the academic year 2014/2015, and grade 11 (1º Bachillerato4 ) during the academic year 2015/16. Students are from a centre in the inland of Galicia (Spain). The thesis focuses on the first year of study with the 4º ESO students. We firstly present the methodological approach on which the thesis is situated. Secondly, the context and participants in addition to the activities developed are outlined, focusing predominantly on those which are the object of analysis in the thesis. Thirdly, the data collected, and the analysis processes are presented. 1.4.1 Methodological approach. Qualitative research This thesis is part of qualitative research which focuses on how people build the world around them, what they do or what happens to them, in order to get a meaningful and varied perspective of the observation of the situation. According to Denzin and Lincoln (2005) qualitative research can be defined as: Qualitative research is a situated activity that locates the observer in the world. It consists of a set of 4 The first year of non-compulsory secondary education. In Spain, compulsory secondary education lasts until students reach 16. Then, they can choose to continue with two more years of Baccalaureate (non-compulsory) until they reach the age of 18, during which they prepare for the university access examination. NOA AGEITOS PREGO 56 interpretive, materials practices that make the world visible. These practices transform the world. They turn the world into a series of representations, including field notes, interviews, conversations, photographs, recordings, and memos to the self. At this level, qualitative research involves an interpretive, naturalistic approach to the world. This means that qualitative researchers study things in their natural settings, attempting to make sense of, or interpret, phenomena in terms of the meanings people bring to them. (Denzin & Lincoln, 2005, p.3). According to these authors, qualitative methodology aims at getting to know social reality by analysing documents or communicative acts. In the context of this study, this methodology is applied in order to analyse students' performance in scientific practices, as well as to investigate how evolution and genetics learning takes place through these practices. Within the qualitative studies, this thesis deals with a longitudinal case study, which enables us to attain in-depth knowledge of a specific case (group of students). According to Gerring (2007), case studies can be explained using the following analogy: There are two ways to learn how to build a house. One might study the construction of many houses – perhaps a large subdivision or even hundreds of thousands of houses. Or one might study the construction of a particular house. The first approach is a cross-case method. The second is a within-case or case study method. (Gerring, 2007 p.1). Case studies are related to social phenomena and they focus on one or more of their manifestations and on their environment (Swanborn, 2010). In addition, they have been carried out for a certain period of time and focus on detailed descriptions, interpretations and detailed explanations, as well as being based on different sources of information (reports, documents, observation notes, among others). In this thesis, Section 1. Introduction 57 the focus is on the first year of the longitudinal study, as this is the first course in which genetics and evolution appear in the curriculum. It is a unique exploratory case study (Yin, 2003) in which the performances of scientific practices are analysed by a group of twenty students in different tasks as part of a teaching sequence on genetics and evolution. One of the most widespread criticisms of case studies is their inability to provide easily generalizable data, given that these are very specific studies (Cohen, Manion & Morrison, 2011). To improve the validity and reliability of the results obtained in the case studies, Moore, Lapan and Quartaroli (2012) suggest applying triangulation. This triangulation can be applied either by using previously tested pilot studies or by using three different sources of information. In this thesis we have used the latter by including: 1) the written reports elaborated by the students; 2) the audio and video recordings of the work sessions; 3) the researcher's field notes. Triangulation is also applied in data analysis in order to guarantee the reliability of the results obtained. The author and the supervisor of the thesis analyse the data related to the research objectives in an independent manner before contrasting the results to ensure homogeneity. In addition, a third expert intervenes by contrasting the analyses of the three objectives, therefore guaranteeing the reliability of the results. 1.4.2 Context, participants and teaching sequence We present the context and the participants of the case study of this thesis as well as the design of the two teaching sequences in which the tasks object of study in this thesis are embedded. 1.4.2.1 Context and participants The context in which the study has been conducted is a secondary school in inner Galicia (Spain). The school, despite being situated in a city, is semi-urban, receiving students both from the centre of the city and several neighbouring villages. Students families have a medium socio-cultural level and a large proportion of the students will continue with their secondary school studies at the end of the ESO, as can be seen in the participants of this study. The participating centre was NOA AGEITOS PREGO 64 session they had to reflect on these cases and write down the advantages and disadvantages of genotype tests. Task 4. Explaining the links between sickle cell disease and malaria: in this case two human diseases, SCD and malaria, were compared by analysing the different data provided. Following Kalinowski et al. (2010), this task was designed to help students to construct explanatory frameworks and make explicit connections between concepts in the context of molecular genetics and evolution. Students had to apply previously used knowledge, for example on mendelian and molecular genetics and evolution to describe the links between two human diseases, malaria and SCD. The reasons for selecting SCD and malaria were as follows: a) among the scientific community their evolutionary relationship is well known given that malaria parasites and humans coevolved providing an adaptive advantage to the SCD heterozygotes; b) these are topics that can be used to address the widespread difficulties reported in the educational research literature concerning the understanding of and relationship between these illnesses (Jarrett, Williams, Horn, Radford & Wyss, 2016); and c) they are relevant to the students, as SCD was recently included in the Neonatal Metabolic Screen in Galicia (Spain). The task was introduced by means of a short discussion with the students. The driving question was presented as follows: “Is there any connection between SCD and malaria?” To try and answer the question, students were provided with a) four numbered envelopes with information and b) a piece of cardboard to arrange the information and write down their conclusions. The structure of the task is shown in Figure 1.4. Section 1. Introduction 65 Figure 1.4 Structure of the task “Explaining the links between sickle cell disease and malaria”. The task was designed to encourage students to use evidence to justify their claims by giving them different data in a structured manner. Students were instructed to open one envelope at a time in numerical order and discuss the information provided, in order, before NOA AGEITOS PREGO 66 writing down their conclusions. This step was repeated four times, each time with a different envelope. The structure of this activity aimed to help students to revise all previous conclusions in the light of new evidence. The information was divided into four sets with information arranged in chronological order, including different types of information related to malaria and SCD, including historical, diagrammatic and genetic information. The information provided has been summarized in table 1.2, alongside the knowledge of genetics and evolution that was required, and a brief description of the epistemic strategies which were needed to solve them. The reason for using a chronological order was to recreate the process followed by scientists, by using the evidence available in order to build a hypothesis and modify it as new evidence emerges. The information was presented both in textual and visual form, as scientific meaning is derived from both modalities of representation (Lemke, 1992, 1998). Students completed the task in one 50-minute session. Table 1.2 Information provided in the task (Ageitos, Puig & Colucci-Gray, in press). Envelope Type of data Information provided Genetics/ evolution knowledge Epistemic strategies 1 Historical First register of a case of SCD Molecular genetics Interpreting historical data about SCD and identifying the shape of the erythrocytes affected by the disease Historical First visualization of the shape of a sickle cell erythrocyte Historical Cases reported in early XX century Visual Image of blood sample with sickle cell erythrocytes 2 Genetic Description of the phenotype of a family affected by SCD Mendelian genetics Completing the family tree of a hypothetical family by interpreting phenotype information using Section 1. Introduction 67 Visual Family tree to complete Mendelian genetics nomenclature Visual Photograph of the members of the family 3 Visual Electrophoresis of heterozygous and homozygous individuals with SCD Mendelian and molecular genetics and biochemistry Identifying: a) the differences between homozygous and heterozygous individuals suffering from SCD, b) the relation between the genotype of SCD and the amount of malaria parasites Visual Amount of malaria parasite in individuals with/without SCD Aetiology Description of malaria 4 Historical Haemoglobin mutation caused by SCD Evolution and Mendelian and molecular genetics Relating the mutation in the haemoglobin of red blood cells to the red blood cell affected by SCD; identifying the distribution area of malaria and SCD Historical DNA sequence mutation identified that causes SCD Visual Maps of distribution of SCD and malaria Teaching sequence 1 ended with a final evaluation activity that was done in the classroom, but without the presence of the researchers. This final activity, entitled “Tracking sickle cell anaemia”, consisted of two questions. The first presented a case of a girl who has sickle cell disease who wanted to travel to areas where there is a high risk of contracting malaria. The second question asked students to use their material models to explain the girl’s illness to her, and for this they were given a colour photograph of their models. Teaching sequence 2, which was developed in the second period (academic year 2015-2016) is related to teaching sequence 1 and was designed considering the difficulties encountered in this first unit. The NOA AGEITOS PREGO 68 tasks are summarised in table 1.3. Since this sequence is not analysed in the thesis, the activities of this sequence are not discussed in detail. Table 1.3. Activities in teaching sequence 2 Activities What were the causes of the deaths of Martiño's pigs? The mosquitoes of Albufera. Can the mosquito population change when faced with an insecticide? Period March 2016 March 2016 Sessions 2 sessions 3 sessions Didactic objectives Apply the model of gene expression to argue about the causes of an animal disease. Evaluate data related to the possible causes of an animal disease. Use available tests to evaluate a deterministic model of gene expression in this context. Evaluate statements related to evolution. Develop a model evolution to explain the Albufera phenomenon. Graphically represent changes in a population over several generations. Relate the developed model to an evolutionary perspective. Revise the teleological arguments based on the model of evolution which has been elaborated. Scientific practices Argumentation Modelling and argumentation 1.4.3 Data collection The data collection took place during the regular course of the different sessions. The researcher, who attended six sessions, played the role of a non-participating observer in order to ensure that they did not influence the development of the sessions. Four instruments were chosen for data collection and triangulation: 1) teachers' surveys, 2) written task reports, 3) audio and video recordings, 4) the researcher's field notes. 1. Surveys: Before the implementation of the tasks, a survey of six open-ended questions was conducted for the teachers involved. The survey was aimed at getting to know their experience and knowledge of scientific practices, in particular regarding modelling. The main purpose was to identify their vision regarding this work methodology. Also, given that a teacher had previous experience in research about modelling, the survey aimed to find out how he assessed the introduction of models and modelling in science teaching in his classes. Section 1. Introduction 69 2. Written reports: These included the written materials produced both individually and collectively in the two analysed tasks, which were: the representations of the gene expression models and the written explanations from each group (Task 1); the written reports where they placed the data provided in Task 4 and the partial and final conclusions drawn. 3. Audio and video recordings: The purpose of these recordings was to record the participants’ discourse and their interactions among themselves and with the teacher while performing their tasks. A total of five sessions were recorded. Before the beginning of each session, the researcher and a collaborator from the research group set up a video recorder and an audio recorder to ensure that everything that happened in each group would be recorded. The video images are necessary in order to conduct a multimodal analysis and identify each member of the group when they are speaking. It is also necessary to check which elements they were handling during modelling and when elaborating arguments from data. The literal transcription of the interactions in the groups and with the teacher is produced for subsequent analysis. 4. Field notes. The researcher was in charge of collecting field notes for each of the sessions. These notes included the distribution of tables and groups in the classroom, comments on the progress made in different tasks, incidents, schemes and drawings made by teachers on the blackboard, as well as difficulties observed during the development of the activities. 1.4.3.4 Data analysis This section presents the main analysis strategy adopted in this thesis, the discursive analysis, as well as the process which was followed in order to address the objectives and research questions. 1.4.3.4.1 Discourse analysis As Ibáñez García (2014) points out, philosophical study traditionally focused on the inner and private world, but with the socalled linguistic turn, the work began to focus on the study of linguistic NOA AGEITOS PREGO 70 statements. Therefore, we move from considering language as a means for expressing ideas to its role as an instrument for constructing them. Over the last decades, discourse analysis has become a theoretical perspective related to learning in social environments, the definition of which we have taken from Gee and Handford (2012): Discourse analysis is the study of language in use. It is the study of the meanings we give language and the actions we carry out when we use language in specifics contexts. (Gee & Handford, p.1). According to Gee and Handford (2012), discourse analysis can be approached in two different ways, one based on linguistic analysis (content analysis and grammar) and the critical approach, which aims to provide a description beyond language functioning, social problems and controversies present in society and, therefore, in discourse. This thesis combines both approaches, as it incorporates rhetoric into the analysis of argumentation on socio-scientific issues. Bearing in mind that teaching is a social activity, language is therefore important for understanding how learning takes place in a classroom situation (Lemke, 1990). For example, in the science classroom teachers play the role of information conveyors that students must subsequently understand and communicate, sometimes through oral language (Jiménez-Aleixandre & Díaz de Bustamante, 2003). People involved in science teaching and learning, therefore, "speak science," as Lemke (1997) indicated. This implies not only learning the language of science, but also its values. According to Gee (2005), discourse can be an identity tool shared by members of a community. In this sense, classroom discourse can provide knowledge about the students' understanding of certain topics, but it can also provide information about values, beliefs, or ideologies. In the last decade, discourse analysis has evolved towards the socalled multimodal discourse analysis (hereinafter MDA). It is considered that social actors perform different actions although, they are not exclusively discursive (Norris, 2004). MDA extends the study Section 1. Introduction 71 of language by combining it with images, scientific symbology, actions, music, sound or gestures (O´Halloran, 2013). For this reason, in this thesis we chose this method of analysis, since in the science classrooms, specifically in the one studied in this thesis, students not only discuss science verbally, but also construct models (representations) to explain natural processes that will be analysed together with oral and written language. In summary, studies that use discourse analysis allow us to know how the knowledge constructed by students is moulded, and at the same time, it is moulded by discourse and social practices. 1.4.3.4.2 Data analysis process Data analysis was performed following the series of steps summarised in Figure 1.5. Figure 1.5 Data analysis process. NOA AGEITOS PREGO 72 First of all, the audio data was transcribed in order to analyse the speech and be able to study the meaning of the language used (Gee, 2005). Since transcription is a change of medium, this leads to a change in the data (Gibbs, 2012). The transcription is done as literally as possible, respecting the terminology used and also the language (Galician, Spanish). From the transcription, the unit of analysis is the turn of speech, this means that each intervention by the participants in the conversation, or a fragment of said turn if different statements or operations are reflected in it. After a first reading, turns can be compiled into episodes, the latter being made up of several turns related to the same discussed issue or the same performed action (Gee, 2005). In consecutive readings, categories are assigned to oral interventions and actions, trying to highlight the aspects which are to be analysed. In some cases, the focus will be on modelling and argumentation operations, as well as their interactions. In other cases, it will focus on discursive moves and rhetorical strategies, but it will depend on the research question which is to be answered. Table 1.4 summarises the analytical tools used for each objective, as well as the tasks that are analysed. Table 1.4 Objects and analysis tools used in each activity to address the research objectives Research objective Object of analysis Analysis tool Sequence task O1. To examine how modelling and argumentation interact and connect the three worlds of knowledge in the context of learning gene expression Modelling and argumentation processes. Interactions between both. Relationships between the worlds of knowledge in modelling. Argumentation operations (building upon Jiménez- Aleixandre et al 2014) and modelling operations (adapted from Schwartz, 2009) Worlds of Knowledge (adapted from Tiberghien, 2000). Modelling gene expression to explain sickle cell disease Section 1. Introduction 73 To examine secondary students’ arguments and the data used while developing explanatory links between two human diseases in genetics and evolution instruction. Quality of written arguments (causal language and application of genetic notions) Causal structure of arguments (Ryu & Sandoval, 2012); Genetics and evolution considerations (adapted from Zohar & Nemet, 2002) Explaining the links between sickle cell disease O3. To examine the intersections between rhetoric and argumentation, and epistemic actions in students’ discourse in the contest of learning genetics and evolution Argumentation (use of tests) and rhetoric in oral discourse. Epistemic actions in discourse Rhetorical moves (Swales, 1990). Frames of thinking (Pontecorvo & Girardet, 1993). Epistemic actions (adapted from Pontecorvo & Girardet, 1993) Explaining the links between sickle cell disease The analytical process took place in interaction with data and existing literature, since we understand that analysis should not start from predetermined categories (Kelly & Takao, 2002), but should instead be defined in interaction with literature and the data itself. It consisted of a process of analysis that involved several cycles of reading the transcripts and reviewing the categories. These categories were elaborated from rubrics collected in the literature (see table 1.4), before being adapted to our data. The final refinement of the categories was negotiated between the various researchers involved. The rubrics for analysing both the responses to the written documents and the models were produced in a similar way, i.e. in interaction with the data itself and taking the literature into account. 1.3.4 Ethical considerations Since the research design involves analysing the data obtained directly from secondary classrooms and working with students and teachers, a number of ethical considerations were taken into account to NOA AGEITOS PREGO 172 Considering that the task engaged students in building a representation to explain gene expression, modelling operations were more frequent than argumentative ones. Operations related to the metaknowledge of modelling (Schwarz et al., 2009), were the least common operations. The task design may have affected this, given that a kit was provided, meaning therefore that students paid more attention to manipulative operations such as “Building the model” than to others. Students spent time selecting and placing the elements provided in the kit to build their representations. This part of the modelling process in which students selected and moved elements from the kit around, glued them or transcribed and translated the sequences corresponded to “doing the lesson” (Jimnez-Aleixandre, Bugallo-Rodríguez and Duschl, 2000). Considering that this was the first modelling-based task in the teaching sequence performed by students this was not an unexpected result. Students may have needed get used to these kinds of modelling-based activities and this may partially explain why participants focused on building the model in the physical way. Regarding the argumentation operations, the use of evidence played a central role, appearing throughout the modelling process. It is the only operation which connects the three worlds of knowledge. This operation includes two subcategories called “Identifying and interpreting data as evidence” and “Using evidence to support a claim: identifying and interpreting evidence”. Students engaged in these subcategories when they identified data from the three worlds of knowledge as being evidence of gene expression and included them in their representations. Another operation related to use of evidence is “Asking for evidence, data and/or justifications” and it also appears in connecting the three worlds of knowledge, but in a lower frequency than use of evidence. The operation of critiquing did not appear frequently when modelling gene expression. This operation involves students questioning certain elements provided in the kit as part of gene expression. The fact that students included the elements in their final representations, despite not being sure about their participation in gene Section 3. Discussion 173 expression, is an indication of their difficulties in engaging in critique. Furthermore, few students made counterclaims, this means that they did not usually propose an alternative idea to the one that was criticised. Regarding the connections among the three worlds of knowledge, connections between the world of theories and the world of representations were more frequent than the connections with the natural world. Students retrieved their knowledge about the elements and processes involved in gene expression to build their representations, which could explain why they established more connections between the world of theories and the world of representations than with the natural world. Moreover, references and connections to the natural world were the scarcest, and, as expected, when students linked it to the world of theories no modelling operations appeared. The examination of RQ2 demonstrated that a relationship exists between the connections established among the three worlds of knowledge and the interactions performed between argumentation and modelling practices. A highest frequency of interactions led to more connections among the three worlds of knowledge. On top of this, this seemed to also affect the elaboration of a more sophisticated representation of gene expression. 3.1.2 Students’ arguments and data used while making links between two human diseases The second research objective, To examine secondary students’ arguments and the data used while developing explanatory links between two human diseases in genetics and evolution instruction, is articulated in these two research questions addressed in Paper 2. RQ3) What is the nature of students’ arguments while explaining the evolutionary links between two human diseases? NOA AGEITOS PREGO 174 RQ4) What data do students mobilise and how do they use them to support their arguments regarding the relationships between these two diseases? The examination of these two research questions focuses on the arguments produced in a task that required students to link two human diseases, SCD and malaria. Particular attention has been placed on the students’ written final arguments (in the case of RQ3) and on the written statements provided by the groups in each step of the task (in the case of RQ4). The analysis of RQ3 allows us to identify the quality of arguments in terms of empirical and theoretical criteria. The results showed that the students’ final written arguments did not include genetics and evolution concepts. One group mentioned the word “evolve” in the third written conclusion but failed to do so in the final argument. They explained that Africans have evolved variants to protect against malaria, but no further information or processes were included. Most of the groups (four out of five groups) were not able to include genetics and evolution concepts in their final written consensual arguments. They focused more on describing some of the data provided instead of developing a final conclusion regarding the links between SCD and malaria. One group was able to use genetics notions as mutation. However, they seemed to have a teleological view regarding the role of mutation in the relationship between both diseases. Students struggled to draw up quality written arguments using clear causal language and building strong justifications. Likewise, the students' explanations seemed to pose naïve ideas about genetics and evolution such as teleological considerations. Teleological explanations, which involve attributing evolutionary change to need, are not rare in students’ discourse (Alters & Nelson, 2002; Zohar & Ginossar, 1998). For instance, students in this study considered that the relationship between the two human diseases is based on the fact that SCD is a protection against malaria. Moreover, one group explicitly Section 3. Discussion 175 attributed to humans, the need for the mutation to appear in order for a protection against malaria to be created. This result is consistent with the one proposed by group 1, who, despite acknowledging that a mutation can be positive, explicitly stated that “black people” can control this mutation based on their own will, therefore revealing teleological positions. The analysis related to the use of data is relevant to this task as it was designed following a structure in which students were provided with data in diverse steps to help them to progressively analyze the data. Their intention was to help students to reach a final conclusion, building on all of the data provided and revising their own arguments in the process. However, when analyzing how they select and modify the data provided, students in our study struggled to integrate this data into their explanations. This analysis helps uncover cultural and social representations. Students identify the origin of SCD in Africa and link the disease to “African-Americans” or “black people”. This issue has already been reported (Jarrett et al., 2016) even though many African- Americans have never even resided in Africa (Biggs et al., 2002). The fact that students identify the idea that this group could only marry among their ethnic group demonstrates that this group has been identified as being marked by cultural differences to other groups at that time. The social representation of identifying all black people not just as Africans, but also as African-Americans appeared in the students’ arguments as in previous studies on argumentation in genetics learning (Puig and Jiménez-Aleixandre, 2011). This points to the influence of cultural knowledge when students try to make sense of the data. 3.1.3 Examination of rhetoric, argumentation and epistemic actions To address the third research objective, To examine the intersections between rhetoric and argumentation, and epistemic actions in students’ discourse in the contest of learning genetics and evolution, two research questions were proposed in Paper 3. NOA AGEITOS PREGO 176 RQ5) What frames of thinking emerge from the examination of students’ rhetorical moves and use of evidence when they are learning about topics in genetics and evolution? RQ6) What epistemic actions help students to make explanatory links between genetics and evolution? The analysis of the oral discussion during the activity Explaining the links between sickle cell disease and malaria allowed us to explore the use of evidence and the rhetorical moves. This analysis helped us to uncover students’ frames of thinking and the epistemic actions performed by the students. Three central frames were identified. Frame 1, Identifying the origins of sickle cell disease in the African community, which showed students’ explanation of the origin of SCD as being in Africa. This claim appeared repeatedly in subsequent frames, demonstrating how students accommodate new data to fit into their own views. Frame 2, identifying the pattern of inheritance of SCD, in which students identified the pattern of inheritance of SCD, as a dominantrecessive pattern, following a discussion on sex-linked inheritance. Besides, they discussed the molecular relationship between SCD and malaria, making connections to the previous frame by recalling the origin of SCD. In frame 3, Making evolutionary links between SCD and malaria, students agreed that there is an evolutionary link between the two diseases. However, the link consists of a relationship between the mutation that causes SCD and the protection that it provides against malaria. The identification of these three frames of thinking allowed us to see the perspective from which students argued and analysed the provided data in the context of linking two human diseases. It seems that using more rhetorical moves helped participants to mobilize more data, although not necessarily demonstrating high levels of using evidence. The highest levels of use of evidence were strongly related to the enthymemes, although they did not seem to help students to achieve a more sophisticated idea about the processes being studied. Section 3. Discussion 177 In accordance with Tibell & Harms (2017), students struggled to build interconnected biological explanations, in particular they struggled to connect biological entities and processes from different levels; between molecular genetics and mendelian genetics or genetics and evolution. This finding points to the need for both engaging students in learning genetics and evolution together and for developing teaching units to help deal with these difficulties (Kampourakis & Zogza, 2009). The examination of RQ6 helped us identify the epistemic actions that appeared in students' discourse. Regarding the analysis of the epistemic actions, Interpreting actions, phenomena and intentions of actors was the one that appeared most frequently in the students’ discourse. The authors expected this result given that biological processes involve different actors that need to be considered in order to be understood. The epistemic action of Locating events and phenomena in time appears very frequently in the first frame, as it coincides with the moment in which the historical data is provided to the students. The epistemic actions of Terminological and conceptual definitions and Locating events and phenomena in time are absent in frame 3. This difference, in comparison with the previous frames, may be crucial in understanding why students are not able to build a complex evolutionary explanation at the end of the task. They did not seem to be able to propose the mechanisms that may be involved in the relationship that they agree exists between both diseases. 3.2 GENERAL DISCUSSION The analysis of data and the use of evidence is a guiding means throughout this thesis. In the first article we saw the fundamental role it plays, with the use of the evidence operation being the most frequent and the one that allows for the three worlds of knowledge to be connected. The role in paper 2 and paper 3 was given by the task design itself, which required students to analyse and use a series of data or information at different epistemic levels in order to reach a final conclusion about the relationship between SCD and malaria. In this case, the results showed that the students always used the data provided, but that they sometimes adjusted this data based on their previous ideas NOA AGEITOS PREGO 178 influenced by social and cultural constructions. In addition, the use of data as evidence for elaborating arguments about the relationships between the two diseases allows, together with rhetoric, for frames of knowledge and epistemic actions that operate in this context to be identified. In the case of paper 2, the analysis of the data used by the students in their written arguments suggested the existence of naïve ideas regarding genetics and evolution. Some of these naive ideas were related to teleological explanations, and some to social representations related to the origin of SCD in Africa. In order to explore this in depth, the oral discourse of a group in which discursive interactions were frequent was analysed. The analysis of rhetoric, in particular of rhetorical moves, was introduced into the study of argumentation. This allowed for the frames of thinking related to the ways of reasoning about genetics and evolution to be identified. This analysis of oral discourse allowed us to verify the appearance of teleological explanations among students, as well as the influence of cultural learning on the interpretation of historical data. One such example was their understanding that African-Americans could only marry other African-Americans and the idea of SCD being a contagious disease that was spread in Africa by an African-American slave before being passed on through inheritance within the African-American community, also appeared in the students' discourse. We also found that students were not able to verbally construct a more sophisticated explanation of the relationship between malaria and sickle cell disease. The absence of epistemic actions such as Locating events and phenomena in time and Designating terminological and conceptual definitions could affect the fact that this group was not able to elaborate a sophisticated explanation in which the coevolution of both diseases would be beneficial for humans. Another common issue that emerged from the analysis presented in the three papers was related to the students' difficulties in moving Section 3. Discussion 179 among the different levels of organization (molecular, cellular and individual) as was also reported in previous research (e.g. Marbach-Ad and Stavy, 2000; van Mil, Boerwinkel & Waarlo, 2013). Following Knippels’ (2002) instructional model for genetics, so-called “yo-yo learning”, our tasks were designed to enable students to move up and down through different organizational levels of biology. In the first task, which has been analysed in paper 1, the materials provided in the kit were related to the molecular and cellular levels, and the affecting disease on an individual level. The task addressed in papers 2 and 3, regarding the evolutionary links between both diseases, presented data from these levels but also from the population level. Students struggled to discuss, in depth, the molecular data presented that could have helped them to build an evolutionary explanation. They also struggled to link the phenotype with the protein function outcome in the first task, and this is consistent with previous studies about modelling in genetics (Reinagel and Bray Speth, 2016). Another difficulty they faced was in linking the phenotype with their representations. This could be related to the “macro–micro” problem, which also requires understanding phenomena at multiple levels of organization. 4. CONCLUSIONS AND EDUCATIONAL IMPLICATIONS In this section we summarise the conclusions drawn from each research question. We then go on to discuss the educational implications that can be drawn from the study and its limitations. Finally, potential future lines of research related to this thesis are presented. 4.1 CONCLUSIONS Conclusions are presented in relation to the three objectives (4.1.1, 4.1.2 & 4.1.3) of the thesis. 4.1.1 Modelling and argumentation and their connections to the three worlds of knowledge The examination of O1. To examine how modelling and argumentation interact and connect the three worlds of knowledge in the context of learning gene expression, allows us to establish five conclusions: Conclusion 1. A range of argumentation and modelling operations were identified while the students modelled gene expression in the context of explaining a human disease. The meta-knowledge operations of modelling were scarce. The analysis of students’ discourse during the modelling-based task has enabled us to identify a set of modelling and argumentation operations. The identification of modelling operations adds a deeper understanding of the elements that appear in the practice of modelling (constructing, using, evaluating, and revising scientific models), to Schwarz et al.‘s framework (2009), this includes the meta-knowledge that guide this practice. The identification of argumentation operations builds on the proposal made by Jiménez-Aleixandre, Puig, Bravo & NOA AGEITOS PREGO 188 4.2 EDUCATIONAL IMPLICATIONS The educational implications that may be drawn from the conclusions are described in the following paragraphs. From conclusions 1, 2, 3, 4 & 5, which are related to the first research objective, the educational implications are: Modelling tasks based on MDM is revealed to be of use to teachers when designing and guiding modelling instruction, and to students when engaging in different operations during the modelling process (Puig, Ageitos & Jiménez-Aleixandre, 2017). The communication stage seems to help students to engage in revising their models, therefore favouring their enrichment. Providing a kit for modelling gene expression seems to be useful for identifying and locating cellular entities and molecular processes (transcription, translation) that are neither visible nor easy to connect. This shows the benefits of engaging students in the elaboration of a material model of gene expression. However, the results show that students still struggle with relating the genotype and the phenotype and with making interconnections among biological levels. In future implementations we would recommend for students to be asked to give explicit explanations as to how they move between the levels of organization during the process of modelling. Modelling tasks offer students opportunities to build and evaluate explanations of the natural world (Mendonça and Justi, 2013), however, as this study shows, this process requires scaffolding. Modelling must present a clear goal for students beyond just "doing the lesson" (Jiménez-Aleixandre et al., 2000). These activities may be performed mechanically if the interaction between practices and between the worlds of knowledge is not articulated. Teachers must repeatedly make the context and objectives explicit during modelling to ensure that students do not lose sight of them. In other words, teachers must use ‘modelling talk’ in an explicit manner. This study shows that students struggle to make connections with the natural world that corresponds to SCD. The phenotype of this Section 4. Conclusions and educational implications 189 disease is microscopic, and this might not help students to recognize it and connect their representations with the natural world. An educational implication is the need to provide recognizable phenotypes, such as achondroplasia or polydactyly, which can be modelled in order to help students make connections to the natural world. Moreover, diseases with a clear environmental influence, such as phenylketonuria could be modelled as a way of helping students to incorporate environmental factors involved in gene expression. Furthermore, we suggest making the worlds of knowledge explicit during the modelling process so that students are able to relate the representation to the theory and apply knowledge to build and explain the representation. The study reveals that the “Use of evidence” operation helps connect the three worlds of knowledge, allowing the scarce connections with the natural world. This points to the central role of this operation. We believe that promoting this operation could increase the connections to the natural world and could therefore be beneficial for the students’ understanding of gene expression. Teachers’ training on how to promote and scaffold the use of evidence in modelling-based tasks requires further attention and research into modelling-based learning. We also suggest the importance of guiding students in the metaknowledge of modelling in a way that makes the modelling practice meaningful for them (Schwarz et al., 2009). For instance, by asking them to reflect on the criteria used for making modelling decisions, such as selecting and including elements in their representations; or by guiding students in the comparison of their representations in a way that will help them to understand that models can take different forms. The operation of critiquing is scarcely performed by students in the context of building a model of gene expression. This indicates the importance of paying attention to the promotion of critiquing in the construction and evaluation of models. Social interactions oriented towards this epistemic goal should be promoted in the science classroom. NOA AGEITOS PREGO 190 Therefore, it is important to make explicit the fact that although the activity requires for a representation of gene expression to be built according to modern genetics, there is not just one correct scientific model to relate to in the world of theories. Multiple historical models of gene function exist as Gericke and Hagberg (2007) emphasized. From conclusions 6 & 7 which are related to the second research objective the educational implications are: Regarding genetics and evolution instruction, as Kampourakis and Zogza (2009) stated, we consider that evolution must be learned alongside genetics, engaging students in dialogic discourses and providing experiences in which they are given the chance to discuss explanations and evaluate evidence. Moreover, this type of instruction should cover social representations and cultural learning as this study shows that these topics may affect the construction and evaluation of arguments in light of the data. Likewise, we agree with some authors’ suggestions that students' alternative ideas such as teleological and anthromorphogenic explanations could be considered as a starting point for evolution instruction (Zohar & Ginossar, 1998). Our findings also suggest that there is a need for the teaching and learning of genetics and evolution to be supported through the provision of data that helps students to use their previous knowledge as a way of helping them to build accurate scientific knowledge. Working in the classroom with data may be a way of helping students to understand evolution as a continuous process that is occurring at present and that is connected to our everyday life and even to the diseases that we suffer, such as SCD and malaria. However, this method presents some challenges to both teachers and students. More emphasis must be placed on the students’ understanding of complex notions such as genetics and evolution in biology education research. We propose developing teaching units which are designed to address these difficulties and engage students in dialogic discourses, providing experiences in which they are given a chance to discuss explanations and evaluate evidence. Section 4. Conclusions and educational implications 191 We believe the aforementioned is an important responsibility for biology educators who are preparing students to be active participants in the social, cultural and ecological practices of science. From conclusion 8, 9, 10 & 11 which are related to the third research objective the educational implications are: The analysis of reasoning practices suggests that awareness of rhetorical discourses should be developed further by teachers in order to help students understand how they view biological processes in wider scenarios. To achieve this goal, it will be necessary to provide teachers with instruction on this matter, in addition to further professional development. We believe that by helping teachers to acknowledge the importance of ‘framing’, which is related to the ways in which frames are connected to particular terms (Flodin, 2017) and the manner in which said terms are connected to cultural beliefs as this would help students to become familiar with the use of frames in their discourse. Following the rhetorical perspective, the metaphorical terms which are commonly used in biology (Affifi, 2017; van Dijk, 2016) should be examined explicitly in the classroom and should be decontextualized in order to be able to examine the figurative meanings and help students understand both the biological implications and the metaknowledge behind rhetoric. The findings of this study suggest that epistemic actions are related to the nature of the information provided. These actions play a role in the construction of sophisticated explanations in genetics and evolution learning, given that the biological processes in both domains involve different actors that need to be considered in relation with each other. Tasks designed to mobilize time-related data and/or concepts that need to be defined may enhance the use of the epistemic actions of Locating events and phenomena in time and Designating terminological and conceptual definitions. These epistemic actions are important in order to understand evolution and natural selection. In line with the ideas of Ferrari and Chi (1998) we propose that in order to promote an understanding of the natural selection process, it is important for students to grasp the multiple levels of organization of living organisms, NOA AGEITOS PREGO 192 as well as the different temporal and spatial scales in which evolution operates. The importance of time and space scales has previously been reported for developing the students’ understanding of historical events (Pontecorvo & Girardet 1993), but not for considering evolution and genetics learning together. An educational implication is the need to address these epistemic actions explicitly in relation to the data provided in argumentation activities. 4.3 LIMITATIONS AND FUTURE LINES OF RESEARCH The limitations of this study correspond mainly to its methodological design. Case studies are designed in order to allow for a deep analysis of the reality (Cohen, Manion & Morrison, 2011), therefore this would enable us to get a better understanding of a group of secondary students learning genetics and evolution’s engagement in scientific practices. The drawbacks of the case studies which cannot be controlled before the study is implemented (Yin, 2003) relate to the fact that results are specific to the context, therefore avoiding the generalization of the findings. Besides, by carrying out the study in a real classroom, this means that certain elements cannot be fully controlled. Tasks were designed in collaboration with the teachers, however, the content of the lessons about genetics and evolution that took place prior to the implementation of these units were not recorded or controlled. Aspects such as the dynamics of the groups and the students’ prior knowledge or motivation may affect the development of the units. Moreover, the students participating in the study changed slightly between the first and second unit, as a new school year resulted in new students joining the school and other students leaving it. Another aspect that limits the implementation and development of the study was related to the amount of time which was available for engaging in the tasks. The Spanish curriculum is extensive and engaging in scientific-based activities requires time and sustained practice, as does the teachers’ training on its instruction. A better performance could be attained if there was more time to engage in the tasks and to become more familiar with this scientific-based approach. Furthermore, students were not directly instructed on the meta- Section 4. Conclusions and educational implications 193 knowledge and epistemic criteria regarding the use of evidence and argumentation. Ryu and Sandoval (2012) propose not only explicit learning about the topic but also the epistemic criteria for scientific arguments in order to improve the quality of students’ arguments. We propose three future lines of research in relation to the findings and the limitations of our study: The first research line is related to analysing epistemic beliefs. Baytelman et al. (in press) have demonstrated that epistemic beliefs and prior knowledge regarding controversial socio-scientific issues determine the different types of arguments that students construct (social, economic, ethical, scientific and ecological). In this line, the examination of how the students' epistemic beliefs might affect their ability to include different perspectives such as genetics or evolution could help identify resources to promote students learning. The second line of research is related to a deeper analysis of the metaknowledge of modelling. As the results have shown, difficulties in engaging in the critiquing operation indicate the need to address this operation explicitly in order to promote a less manipulative understanding of modelling processes than the one addressed in the thesis. A third line of research relates to the analysis of emotions in the students' explanations and arguments. The tasks presented in this thesis dealt with diverse human diseases. When designing these activities, the emotional component that could accompany them was not considered. However, this emotional component might influence how students perform argumentation and understand the disease, as well as the way in which the teacher presents the tasks or how the students behave around the topic. We suggest that the analysis of emotions is a dimension that can influence the construction of explanations, providing a greater understanding as to how to benefit from emotions in the classroom to promote students learning. In line with the analysis of emotions in the classroom, an adaptation of the AIR model (Barzilai NOA AGEITOS PREGO 194 & Chinn, 2017) that takes into considerations emotions and values could be developed in further research. We hope that the results of this thesis contribute to improving the understanding of scientific practices such as modelling and argumentation. 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