When I lived with my sister we put things that made a big mess or things that got lost easy, such as puzzles. We would put them on the upper shelves so that if they wanted them they had to ask and we could supervise and make sure they kept the pieces together.
We once had a horrible mess of legos all over the floor kept finding them for days and days. Even found some in the laundry bin have no clue as to how they got there though.
