Geometrical imagination and knowledge of triangles at elementary schools

A pilot study concerning rudimentary knowledge of triangles and spatial imagination is submitted to 7th-grade pupils of an elementary school and students of the same age at a grammar school. The theory is important but practical problems are more interesting for students. Problems in spatial imagination allow a teacher to specify the level of students' mathematical abilities. The aim of this pre-research is to compare knowledge of pupils of an elementary school and a grammar school.