While learning a complex skill in science using a computer-based simulation, optimal timing of information presentation facilitates learning and enhances test performance. An optimal information presentation format is proposed: supportive information is presented before practising a skill, and procedural information is presented during practice. Four information presentation formats were compared in a factorial design with the factors timing of supportive information (before or during task practice) and timing of procedural information (before or during task practice). Eighty-eight third-year high school students (37 male, 51 female; mean age = 14 years, standard deviation = 0.52) participated in the experiment. Information searching behaviour and transfer test performance were studied. The information searching behaviour confirms the hypothesis. Findings on the transfer test are less clear due to a bottom effect.