Do not look directly into the laser light.
Dim the lights in the room and shine the laser on the screen to show students the point of light. Now shine the laser on a record such that the light bounces off the record and on to the screen. A line of spots will be seen.
When the light hits the grooves in the record it is scattered and interference occurs among the resulting light waves. Both constructive and destructive interference occurs leading to a pattern of dark spaces and light spots.