Before and after in the alphabet
All the balls are rolled out on the floor.
The room is divided by a midline. Designate which side is “before” and which is “after”.
The participants take one ball each and move around the room. The teacher calls out a random letter.
Everyone who has a ball with a letter appearing earlier in the alphabet than the one the teacher calls out, runs to the “before” side and those with letters later in the alphabet run to the “after” side.