Title:

Periodic Table in 9th grade textbooks: a critical analysis of the pedagogical approachesAbstract

Portuguese curriculum for the 9th grade recommends an inductive approach to the study of the Periodic Table (PT). Student’s are asked to organise cards containing descriptions of the elements according with their physical and chemical properties and teachers should use these constructions as starting point to a systematic approach of the current PT. Using this method-ology it is possible to teach the organisation of the elements in a naturalistic way and use the PT to go further to the study of the atom. The similarity of chemical properties, that is used to group the elements in families, can be justified by the internal structure of the atom and go straight the to the concept of atomic number.Although the curriculum do not demand the exploitation of the history of the PT, the meth-odological approach suggested is inspired in the History of Science; Mendeleev proceeded in a similar manner using cards of elements known at his time. Using an inductive process to teach this subject is also a way to promote constructivists modes of teaching that care with the ideas of the students. Complex and abstract concepts like the atom structure and the atomic number can be build on top of more common ones like the physical and chemical properties of the elements that can be derived from daily experiences.In this paper I will discuss the adequacy of the recontextualization that Portuguese chemistry textbooks do of this subject to the National Curriculum.

IntroductionDuring the second half of the 20th century, science teaching goals and methodologies changed dramatically. Nowadays, having in mind the importance of scientific literacy (Roth & Barton, 2004) to citizenship, the curricula and syllabus of most european countries recognise the im-portance of, beyond teaching science, teach about science and its relationships with society and technology (Vilches & Furió, 1999). Teaching about science is also teaching taking into account the philosophy and history of science. Teaching scientific subjects separated from the contexts of their production is teaching science ignoring the process by which scientific knowledge is produced, hence is to teach science (facts) without teaching about science.Several studies in different countries, including Portugal, show that textbooks are the main resource used by teachers to plan and organise their lessons (Apple, 2002; Morgado, 2004). Although we acknowledge that teachers may not use the activities purposed in the textbooks, it is our opinion that textbooks should make a contextual presentation of science not only in the everyday life, but also in the history of science. In fact, respecting to the portuguese cur-ricula, if they don’t they are not complying with the demands of the official documents. This is why the quality of textbooks becomes a major issue in science teaching.According to the portuguese curricula, the Periodic Table (PT) should be treated on the 9th grade (14/15 years old students) of the compulsory school. The official guidelines advice teachers to initialise the study of the periodic table before the concept of atomic number. The strategy is to ask students to group cards with the identification of the elements (not necessar-ily all elements from PT) and their main physical and chemical properties using criteria de-cided by them. Using the groups made by students the teacher should then discuss with the students what was the criteria that they used and why they choose that one. Then the teacher should ask the students to organise the cards in groups of elements with similar chemical properties and supported by the new organisation made by students he introduces the organis-ing criteria used in the modern PT. The next step is to investigate the reasons behind the fact that some elements have similar chemical properties. This inquiry conducts to the organisa-tion of the electrons within the atom and to the concept of the atomic number.It is easy to establish parallelisms between the former didactical strategy and the PT history. Not only Dimitri Mendeleev (1834-1907) used cards with the elements atomic weight and properties when he was trying to build a table with to systematise the knowledge about the elements to facilitate this students’ understanding, but also the concept of atomic number was developed only in 1911 by Henry Mosley (1887-1915). The similarity of the chronological order of the historical events and the order of the teaching methodology allows the teacher not only a socio-constructivist and naturalistic approach to the subject, but also to explore histori-cal aspects of the PT construction.In this paper we analyse all the chemistry textbooks from the 9th grade and, by means of con-tent analysis, evaluate the compliance of textbooks with the curricula suggestions.

MethodologyThe atomic structure and periodic table sections of eight 9th grade manuals, corresponding to all the manuals available in the portuguese market, were submitted to a content analysis (Bar-din, 1977). From this evaluation three categories emerged: (A) subject organisation; (B) type activities purposed to students and (C) compliance with the official curricula suggestions.Categories analysis results were classified with three qualitative levels: Innovative, Tradi-tional, for category (A) Innovative, Traditional and Mixed for category (B) and Full, Partial

and No compliance for category C. Of course category C results are based on the results ob-tained in the former categories.On categories (A) and (B) by Innovative we denote the more socio-constructivist and context caring organisation of the manual and type of activities described on the previous section and suggested by the portuguese curricula. Thus, by Traditional we denote the organisation and type of activities related with a transmissive and rhetorical teaching methodology that favours the learning of scientific facts and do not establishes STS relationships neither with historical contexts. This classification is related with a scientific content organisation that starts by in-troducing the atomic number and explains the PT organisation based on this concept and pre-sents the periodic properties of the elements as facts denoted by the PT. Regarding the category C, a manual was classified as Full compliant if it respects the subjects order recommended in curricula and provides activities that allow an methodological ap-proach identical to the one recommended by the curricula. Partially compliant means that the manual respects the order, but it does not have traditional activities like exercises to check the students achievements. Not compliant was attributed to the manuals that maintain the tradi-tional subject order starting the subject with the concept of atomic number and making an ap-proach of the periodic table based on this concept. In this case there was no worry in classify-ing the activities as all the manuals with this classification only purposed de second type of activities mentioned earlier.

ResultsTable 1 presents a summary of results. The second column shows the percentage of portu-guese schools that have adopted the textbook and, between brackets, the total number of schools. Second, third and fourth columns show results of categories A, B and C, respectively.

Table 1 - Results summary of the textbook analysis.

Textbook Schools (%) Category A Category B Category C

A

B

C

D

E

F

G

H

34% (441) Traditional Traditional Not compliant

18% (238) Traditional Traditional Not compliant

18% (230) Traditional Traditional Not compliant

11% (145) Traditional Traditional Not compliant

7% (93) Traditional Traditional Not compliant

7% (87) Innovative Traditional Not compliant

5% (60) Traditional Traditional Not compliant

1% (8) Innovative Innovative Partially compliant

Textbook A uses a traditional approach where it introduces the atomic structure and explains the concept of atomic number. It introduces the PT by stating that elements are organised by crescent order of their atomic number. Although there are some innovative students directed activities, like researches and presentations to the class, the majority are very traditional. This fact associated to the content approach lead us to classify the textbook as Not compliant with

the official curricula. Textbooks B and C are both from the same editor. Their index presents the study of PT before the atomic structure. However, a closer look shows that this is ficti-tious. Before introducing the PT both textbooks present a, summary, rather incomplete and confuse idea of the atomic number and proceed from there to periodic table explanation. Textbooks A, B and C are in use on 70% of the portuguese schools with 9th grade classes.Textbook D characteristics are very similar to textbook A. A traditional approach, some occa-sional innovative activities and a lot of traditional quiz. This lead to the classification of not compliant.Although textbook E does not use the card activity suggested in the curricula, it uses a inno-vative approach to the TP study. It presents the table as an form of organisation of the ele-ments underlying their properties similarities and differences. However the activities are all very traditional and do not give much opportunity to students to participate actively in the contents presentation. Activities present a students’ role of listen and reproduce. This fact conducted to not complaint classification on category C.Textbook F shows a situation similar to textbooks A and B, although it is seriously worsened by several scientific errors.Although textbook G, like textbook D, shows no scientific errors, it shows a traditional ap-proach with few innovative activities.Textbook H, although does not use the card activity suggested by the curricula it has a good and socio-constructivist approach to the PT, complemented by activities of the same type. Textbook H is adopted by less then 1% of the portuguese schools with 9th grade classes.

Final discussionTwo main problems seem to arise from this study: (1) the lack of pedagogical quality of most of portuguese textbooks and (2) the criteria used by teachers when they have to choose a book. Although none of the books was considered fully compliant with the demands of the portuguese curricula, they are by no means all similar. Further research is needed in order to understand the criteria guiding authors in textbook conception and teachers when deciding what textbook to use.

Bibliographic referencesApple, M. (2002). Manuais escolares e trabalho docente: Uma economia política de relações de classe e de género na educação. Lisboa: Didáctica Editora.Bardin, L. (1977). Análise de conteúdo. Lisboa: Edições 70.Morgado, J. C. (2004). Manuais escolares: Contributo para uma análise. Porto: Porto Edi-tora.Roth, W. M., & Barton, A. C. (2004). Rethinking scientific literacy. London: Routledge.Vilches, A., & Furió, C. (1999). Ciencia, Tecnología, Sociedad: Implicaciones en la Educa-ción Científica para el Siglo XXI In Ciencia, tecnología, sociedad: Implicaciones en la edu-cación científica para el siglo XXI: La enseñanza de las ciencias a las puertas del siglo XXI (6 al 10 de diciembre 1999 centro de convenciones pedagógicas cojimar, ciudad de la ha-bana, cuba). Retrievied from http://www.oei.es/salactsi/ctseducacion.htm