The purpose of the study is to investigate the effects on students' analytical thinking of a learning activity based on the analysis of flowing waters, represented on a hypsometric map. 20 students from the 8th grade participated in the study. The experimental design included three stages: in the first stage in which the students were asked to analyze flowing waters based on a map; in the second stage the students analyzed, in groups, the flowing waters represented on a hypsometric map using a worksheet; in the third stage the students solved the task received in the first stage. The results show that the students, after the formative intervention, have a higher level of competence in analyzing flowing waters on the hypsometric map and that the worksheet determined the increase in the level of competence and contributed to the development of analytical thinking.