My school is K-1 only and is so tiny, we don't need crates on wheels. (Plus, we have stairs!) But, our sister school, 2-5, is next door and HUGE!! Lugging lunch crates down to cafeteria and back each day was a pain in the neck. So a fourth grade girl invented a conversion kit for the "lunch lugger" baskets for the Invention Convention. She took the baskets home and retrofitted each basket and added a handle to make lugging the lunches even easier.