The purpose of this research was to explore how adult users interact and learn during an interactive computer-based simulation supplemented with brief multimedia explanations of the content. A total of 52 college students interacted with a computer-based simulation of Newton's laws of motion in which they had control over the motion of a simple screen object--an animated ball. Two simulation conditions were studied, each differing in how the feedback of the ball's speed, direction, and position was represented: graphical feedback consisted of animated graphics and textual feedback consisted of numeric displays. In addition, half of the participants were given simulations supplemented with brief multimedia explanations of the content modeled by the simulation in order to investigate how to promote referential processing, a key component of dual coding theory. Results showed significant differences for both the use of the explanations and simulations containing graphical feedback in helping participants gain both implicit and explicit understanding of the science principles.