The Introductory Physics Pendulum Lab program asks students to develop a model for a pendulum. It is distributed as a ready-to-run (compiled) Java archive. Double-clicking the ejs_intro_PendulumLab.jar file will run the program if Java is installed. In order to modify this simulation (and see how it is designed), if you have Ejs installed, you can right-click within the simulation window and select Open Ejs Model from the pop-up menu. Information about Ejs (Easy Java Simulations) is available at: http://www.um.es/fem/Ejs/. The Intro Pendulum Lab program is one of a suite of Easy Java Simulations (Ejs) models used in Introductory Physics Labs. Ejs, a part of the Open Source Physics Project, and is designed to make it easier to access, modify and generate computer models. Additional models can be found by searching ComPADRE for Ejs.