On this interactive site, visitors with a penchant for velocity-time graphs, kinematics, and the world of motion will be well-served. Created as part of "The Physics Classroom" portfolio of educational materials, this collection of interactive Shockwave files simulate a series of physical situations. Visitors to the site can manipulate a variable in each activity and observe the outcome. All told, the site has around two dozen different activities, and many of them are accompanied by an activity sheet which provides basic directions for users. One of the most interesting activities here is the "Riverboat Simulator", which allows users to explore concepts of relative velocity by investigating the motion of a boat across a river in the presence of a current.