Background:
Pierre M. Van Hiele created five levels of geometric thinking. There have been many studies around the world aiming to recognize the students’ levels of geometric thinking. We decided to investigate the area of students’ development in geometric thinking in Slovenian primary schools.

Materials and methods:
The purpose of this research was to identify the level of geometric thinking in the students, aged 9 to 11 years. In order to do that a test was compiled, consisting of eight tasks.

Results:
The majority of students (60.7 %) are at the transition between the zero (visual) level and the first (descriptive) level of geometric thinking. Nearly a third (31.7%) are at the first level, 4.3 % of students are at the zero level. Only 1.4 % reached the second level of geometric thinking or the level of informal deduction. Students had the most difficulty with the use of appropriate geometric language, so a teaching approach to improve the said mathematical language was created, in an attempt to accelerate the transition to a higher level of geometric thinking.

Conclusions:
The teaching approach that proved successful was based on the use of different materials, concrete experiences, promoting the use of appropriate geometric language and motivation of students.