Support straps (the straps that buckle across your child's chest and hips) are a great idea as the weight of their bag increases. For a backpack that will weigh over 10 percent of your child's body weight, look for a backpack that has a chest strap and waist/lumbar belt. This keeps the weight of the contents centreed as close to the body as possible and allows the legs and pelvis to take pressure off the spine.