Simulations
This is another interactive simulation provided by Wiley that explains Newton's 2nd Law with some very valuable graphs;
A great introductory simulation by PHet;
Another simple tool to look at forces and acceleration by PHet. This simulation uses FBD on the right, make sure you are familiar with that tool. Be sure to turn friction off on the right hand side of the applet, just below the free body diagram;
Other Activities
An online workbook provided by PhysicsLAB;