Khan Academy
Khan Academy: Telling Time on the Number Line
Match time of a number line to time on an analog or digital clock. Graph a given time on a number line. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
American Association of Physics Teachers
Com Padre Digital Library: Open Source Physics: Special Relativity on Rotated Graph Paper Model
A representation of Minkowski spacetime diagrams using graph paper that is rotated, showing the world lines of three stationary observers with light clocks.