During a collision, two objects exert forces on each other that vary in a complex way during the time of the collision. Using Newton's second law to predict the outcome of a collision would thus be a daunting challenge. Nevertheless, some collisions have very simple outcomes that can be predicted by analyzing the motion of the objects before and after the collision. A before-and-after visual overview is therefore an important problem-solving tool in such problems. The following Tactics Box explains how to draw a visual overview focusing on the connection between "before" and "after."