The Ejs Simple Pendulum model displays the dynamics of a simple pendulum. The pendulum is initially displaced from equilibrium and the pendulum bob has zero initial velocity. The initial position of the pendulum bob can be changed by click-dragging the bob when the simulation is paused. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting “Open Ejs Model” from the pop-up menu item. Ejs Simple Pendulum model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_osc_Pendulum.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for Newtonian mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.