The student is shown an image of two alien spaceships in a battle, firing lasers at each other, and is asked to determine based on direction of motion if the laser fire from one spaceship would be redshifted/blueshifted/unchanged from the point of view of the ship being fired upon.
keywords: alien, spaceship, laser, redshift, blueshift
swf file: ca_light_spaceshipshifts.swf