How many cans did the first graders collect for the food drive?

Record an estimate that is:

If the cans from each grade need to stay together in a box, how can the boxes be packed so there are 35 to 65 cans in each box?
Show your thinking using drawings and equations.

If you have time: Can any box have cans from 3 grade levels?
What is the least amount of boxes the school can pack to send to the Food Bank?