I definitely didn't invent this, and you've all probably heard of it already.
If not, keep reading.
Right before the end of the day, our floor is always a mess! The perfect solution...
Look around the room and find one or two pieces of paper (or a crayon, or a pencil...), laying on the ground. Call out, "Magic scrap!" Your students will immediately drop to the floor and begin picking everything up. Whoever finds the magic piece gets a small prize.
It's the best way to get your floor clean in seconds!