Inquiry learning requires the ability to understand that theory and evidence have to be distinguished and co-ordinated. Moreover, learners have to be able to control two or more independent variables when formulating hypotheses, designing experiments and interpreting outcomes. Can sixth-grade (9-10 years) children be trained to acquire these inquiry learning skills? Or is the opportunity to practice in a computer-supported simulation environment a sufficient condition to foster inquiry learning skills? In this study, two groups of sixth grade children were compared: a training group, and a practice group. The training group received an off-line inquiry learning training in which we focused on fostering strategies for proper inferencing and designing experiments. The practice group conducted four inquiry learning tasks during two practice sessions. Learning outcomes and inquiry learning process measures were collected to study whether training and practice resulted in desired changes in learning behaviour. Both training and practice resulted in better performance during the test problems. Compared to the practice group, the training group showed some advantage in discovering an interaction effect. Practice and training effects appeared to be dependent on type of domain.