The following 7 animations are from The Australian National University.
These animations were produced using Mathematica to demonstrate time dilation using light clocks. The notebook can be downloaded. The animations are explained here.
These were produced using Mathematica to demonstrate the invariance of lengths perpendicular to an objects motion. The notebook can be downloaded. The animations are explained here.
This was produced using Mathematica to demonstrate how a curved surface can simulate a force. The notebook. can be downloaded. The animations are explained here.