Tracker

Tracker is a free video analysis and modeling tool. Built on the Open Source Physics Java framework, Tracker combines videos of physics experiments with computer modeling. Key features include object tracking, center of mass tracking, rotational motion data, interactive graphic vectors and more.

Physlets

"Physlet" is short for "Physics Applets." This collection of Java-based applets demonstrates a variety of physical laws and for teachers and students.

Xoscope

Especially helpful for educators teaching lessons on sound, Xoscope turns any Linux PC into an oscilloscope. It can accept audio input from up to eight different channels.

Gnu Octave

Open Source Computation Tool

GNU Octave is a high-level interpreted language, primarily intended for numerical computations. It provides capabilities for the numerical solution of linear and nonlinear problems, and for performing other numerical experiments. It also provides extensive graphics capabilities for data visualization and manipulation. Octave is normally used through its interactive command line interface, but it can also be used to write non-interactive programs. The Octave language is quite similar to Matlab so that most programs are easily portable.