DynamicsLab is an NSF-funded project producing simulations for educational purposes. While the PhET project produces simulations for K-12 and first-year college students, DynamicsLab focuses on more advanced concepts, beginning with phenomena studied in intermediate classical mechanics. The other thing that sets DynamicsLab apart is that users of the software can modify the governing equations, modifying the behavior and even creating non-physical behavior. Giving the student this feature leads to greater understanding of the connections between the mathematical forms and the phenomenon itself. DynamicsLab uses the PhET suite of software libraries so that students who have used PhET simulations in the past will find DynamicsLab familiar and easy to use.