In online learning environments where automatic assessment is used, students often resort to harmful study practices such as procrastination and trial-and-error. In this paper, we study two teaching interventions that were designed to address these issues in a university-level computer science course. In the first intervention, we used achievement badges, a form of gamification, to reward students for submitting early, solving exercises with few iterations, and completing the exercises with full points. In the second intervention, we used heatmap visualizations that show a prediction of the student's success if he or she continues to behave in the same way, based on data from earlier courses. The results from a controlled experiment show that the heatmap visualizations had an impact on how early the students submitted their exercises and how many points they earned from them. We also observed that "performance approach" goal orientation correlated with an interest towards the achievement badges whereas "performance avoidance" correlated with an interest towards the visualizations. The results indicate that increasing students' awareness of their behavior can have a positive impact on their study practices and results. However, the same type of feedback may not suit all students because of individual differences.