M.J. Castillo Céspedes 1, M. Burgos Navarro 2, J. Godino 2

1Universidad de Costa Rica (COSTA RICA)
2Universidad de Granada (SPAIN)
The textbook remains the teacher's preferred curriculum material. It constitutes a source for teachers learning (Nicol & Crespo, 2006), and largely determines what happens in the classroom (Thompson, 2014). The use of the textbook in the classroom involves a critical position on the part of the teachers (Braga & Belver, 2016).

Teachers should be qualified to make critical use of curricular materials as a guide for instructional design, in addition to interpreting the information included in these materials, and make adaptations to solve their limitations (Yang & Liu, 2019). However, studies have shown that these actions are often difficult for novice teachers (Beyer & Davis, 2012).

We describe and analyze a formative intervention with 61 prospective primary school teachers, which was aimed at developing the textbook lesson analysis competence. We proposed to these prospective teachers to systematically analyze a lesson on proportionality, by applying the Didactical Suitability Theory facets and components (Godino, Batanero, Font, Contreras & Wilhelmi, 2016). The choice of proportionality is due to the importance that its study receives in the curricula of Primary and Secondary Education, and that proportionality is not usually adequately presented in textbooks (Shield & Dole, 2013).

The written reports produced by 14 work-teams are compared with the a priori analysis carried out by the researchers. The results analysis reveals that the epistemic deficiencies of the lesson were not clearly identified by the prospective teachers, thus revealing their limited didactic-mathematical knowledge on proportionality and their lack of critical evaluation of the textbook.