Give students pocket lasers, small mirrors, and tape.
Ask them to reflect the laser around the room.
It is more challenging than expected, as a slight change of angle of the mirror will change the direction of the laser dramatically.
Very fun, but very dusty for other objects in the room: clap cornstarch in the air to visualize the laser beams. Students can design a challenge where they have to crawl under and climb over laser beams without touching them.