Research on balance rule learning has focused on studies done in individual settings. This study investigates how students collaboratively learn balance rules and focuses especially on four variables that potentially affect rule development: student age, group composition, prior knowledge, and scientific reasoning skills. Eight-, ten- and twelve-year-old students collaboratively used a designed simulation-based learning environment with an open experimentation space and tasks that required progressively more complex balance rules. Students’ balance rules were tested before and after intervention with the Balance Scale Test and their scientific reasoning skills were tested with items from the Science-P Reasoning Inventory. The results show that the intervention was successful in developing students’ balance rules. Logistic regression show that the students’ previous knowledge was the only variable that affected the likelihood of rule development. Students’ with less complex pre-test rules developed their rules more often than students with more complex pre-test rules when controlling for the other variables. The results go against some previous findings and show that a collaborative setting can lead to balance rule learning with primary school aged students.