In this study we explored the effects of providing ninth-grade students with the chance to take part in decision making concerning the mathematics level they would be assigned to in high school. Decisions concerned their self-competence regarding their mathematical abilities, their learning goals and the class atmosphere. The students were taught three mathematics topics during the ninth grade in two levels (regular and extended) and after each topic they were examined in the level they identified as appropriate for himself/herself. After each exam the students were asked to fill in a questionnaire in which they had to address issues referring to their choice. The results revealed that the students learnt how to better monitor their learning. The students' learning goals were mainly performance and mastery goals and the class atmosphere changed completely and frustration and dissatisfaction were no longer expressed. (Contains 2 tables and 3 figures.)