Interactive simulation of travel to six different stars at selected speeds. A comparison of the time elapsed on Earth vs the time elapsed on the spaceship. Upon arrival back to Earth, information about how Earth has may have changed during the time gone on the trip is shown.
A mixture of games, simulations, quests, and other educational topics all from a project originally called Games To Teach (archives are available, but notes on the site direct you back to the Education Arcade area. Games in the GTT area are interesting as well -- green games, etc.