Compartments prevent items from shifting and ensure it can't be over-packed. In addition to wide shoulder straps, make sure your child doesn't sling his or her pack over just one shoulder. Children should sit with feet flat on the floor and hips level with the knees. Commercially available seat wedges or desk slopes can help correct a poor fit. Backpack Safety America has an illustrated guide aimed for schoolchildren.
Photographs also show how wearing a backpack slung over one shoulder distorts the spine.