The Tracker video analysis and modeling program enables students to create simple particle model simulations based on Newton's laws and to compare their behavior directly with that of real-world objects captured on video. Tracker's "model builder" provides a gentle introduction to dynamic modeling by making it easy to define and modify force expressions, parameter values and initial conditions while hiding the numerical algorithm details. Because the model simulations synchronize with and draw themselves right on the video, students can test their models experimentally by direct visual inspection, a process that is both intuitive and discerning. This leads them to move from a paradigm of "problem solving" to one of "model building and testing" that reflects more closely the activities of professional physicists. Tracker is part of the Open Source Physics project.

Tracker is available at <http://www.cabrillo.edu/~dbrown/tracker/> or from the comPADRE Open Source Physics collection at <http://www.compadre.org/OSP/>. Partial funding was provided by NSF grant DUE-0442581.

Please note that this resource requires at least version 5 of Java (JRE).