Abstrakt
Chemical reactions are among the key and critical points of chemistry teaching in lower secondary school. The difficulty of this topic relates to its complexity, which includes a large number of different types of reactions and their inconsistent classification.
As part of the solution of the project OP RDE "Didactics: Man and Nature A" focused on the initial curriculum of natural sciences, an innovation of teaching the topic of chemical reactions was proposed in the form of implementation of experimental cycles. By analysing their course, including the classification of partial chemical reactions according to selected criteria, learners acquire knowledge of this issue.
Calcium cycles that have a connection with everyday life and do not pose such safety risks as, for example, copper cycles have proven to be most suitable for pupil experimental performance. In this paper, we present a concrete form of laboratory exercise involving a cycle of calcium.
The original proposal was first commented by practical teachers and subsequently verified by action research in various regions of the Czech Republic. Teachers received the laboratory exercise favourably, but recommend e.g. the first step, i.e. thermal decomposition of calcium carbonate, to be carried out by the teacher.
Based on the teachers' comments, modifcations to the laboratory exercise were proposed.