This study focused on differences between teacher-centred and learner-centred experiments in soil ecology. After a pilot study, we selected three experiments simple enough to be carried out by pupils even with little experience in self-determined learning and hands-on practice. The sample comprised 123 fifth and sixth graders from a middle school (four classes). We found a significant influence of treatment on achievement and pupils enrolled in a learner-centred environment scored higher. Girls scored higher than boys in both treatments. We found no differences in well-being, boredom or difficulty of the tasks, but pupils of the learner-centred group expressed a higher interest. (Contains 3 tables.)