PRIMARY STUDENTS' REASONING IN PROBLEM SOLVING AND TEACHERS' EVALUATION OF THEIR ARGUMENTS

We examine 5th and 6th grade students' ability to reason during problem solving activity and teachers' evaluation of their arguments. Three tasks were distributed to 236 students asking them to decide on the conclusion and justify their decisions. Indicative examples of the students' responses were given to 16 teachers for assessment during semi-structured interviews. The results suggest that a considerable proportion of students provide no mathematical justification and another proportion supported their argument on numerical examples. Some teachers were found to value justifications based on numerical examples as equally good and occasionally even better than mathematically valid statements. It seems that any effort for improvement should start from changing teachers' views and didactical processes.