In Spring 2007, introductory mechanics students at Cabrillo College used Tracker to compare 2D particle models with videos of real-world motion. After doing a traditional motion video analysis lab, students used both analytic (position functions) and dynamic (force functions and initial conditions for numerical solvers) models to draw overlays directly on their captured videos. The video thus provided a "reality check" while students explored different models, parameters and algorithms. In addition to the visual overlays, the models generated "experimental data" for graphing and analysis just like experimental (student-marked) tracks. This paper will describe my own and my students' experiences with this first exposure to computational physics in the curriculum. Tracker is a JAVA video/image analysis tool developed by the Open Source Physics Project. The Open Source Physics project is supported in part by the National Science Foundation grants DUE-0126439 and DUE-0442481.