Abstract:

We present a study that deals with the pedagogical content knowledge (PCK), its development and the implications for the professional development knowledge of science teachers and preservice teachers, in particular for those who teach chemistry.

In the teaching and learning processes of science, especially chemistry, the contents must be approached from the integration of three representation levels (macroscopic, microscopic and symbolic) that characterize the discipline. However, understanding these three levels depends on how the teacher guides the processes. For example, the use of analogies and the connection between levels (resources and content organization), improve students' ability to solve chemical problems and understand chemical phenomena. In this line, the repertoire of methodological strategies (PapEr) acquires great importance, that is, how the teacher organizes and develops their class. Our objective is to identify and describe the repertoire of activities, strategies and resources used by high school chemistry teachers, with performance levels of excellence (competent and outstanding).

For the methodology, a sample design with a 5% error and a 95% confidence interval was proposed. The initial sample was 86 videos of chemistry classes by high school teachers evaluated between the periods 2011, 2012 and 2013, which once reviewed and validated were reduced to 82 videos. To collect information that appears in the teachers' practice and that we observe in their classes, we use various qualitative-descriptive instruments (registration guideline, list of symbols, systematization and coding guideline, and symbology guideline). For the information analysis and data generation, we use categorical content analysis (activities, strategies and resources) and quantitative techniques such as classical statistics (variance, mean, deviation) and multivariate (correlations and Student's t). In addition, we use the variables of gender and performance level to establish correlations.

The main results indicated that the teachers in the study tend to implement classes with highly homogeneous characteristics where gender or performance level are not variables that influence the activities, strategies or resources used in teaching chemistry. A difference was only found in the frequency of the strategies variable "explains or exposes content" where it is observed that the men in the study use this strategy more frequently than the women. According to what has been observed, it is evident that, in general, the teachers in this study use practices that are more focused on the exhibition and monitoring of content, using as many technological resources as traditional resources. On the other hand, classes that incorporate strategies or practical activities such as experimentation, exercises or modeling were observed less frequently. Resources used, such as science-specific materials, are also found less frequently. When making comparisons according to the gender of the teachers or their level of performance, in general, do not differ by these variables.

Examining in detail the practices for the teaching of chemistry, especially if we talk about examining the practices of excellent teachers, constitutes a necessity and a strategic aspect, which is related to the possibility of replicating (modeling and transferring) practices quality in the classroom, develop professional knowledge and improve teacher training processes.

Keywords:

Paper, activities, strategies, resources, teacher training, chemestry, professional devolpment of teacher.