Khan Academy
Khan Academy: Use Matrices to Transform 3 D and 4 D Vectors
Find the result (both algebraically and graphically) of transforming a vector using a transformation matrix. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Math Planet
Math Planet: Geometry: Transformation Using Matrices
Explains how simple polygons translate into matrices and how to use 2x2 matrices to represent transformations in a plane. Includes video demonstrating an example where a vector must be rotated 90 degrees using matrices. [4:18]