Your preschooler can't wait to wear her new big-girl backpack--and you can't wait for her to carry some of her own crap for once. But you don't want to weigh her down. Follow these backpack basics:
Keep it small. Your tot can't--and shouldn't--handle a full-size Jansport. Look for bags that are specifically designed for little guys, like the adorable animal-shaped Zoo Packs from Skip Hop ($20; skiphop.com).
Keep it light. Your child should be able to walk upright and with ease while toting her pack, which shouldn't weigh more than 10 percent of her body weight, says Donna Goldberg, author of The Organized Student. For a 30-pound 3-year-old, that's just three pounds--the equivalent of a sippy cup of water, a book or two, a lovey, and the backpack itself. Leave the Polly Pockets collection at home.
Keep it on her shoulders. Teach your child that her backpack has to be worn on both shoulders (slinging it over one shoulder can cause neck and back strain). Look for a style with padded straps, and adjust them so the pack is tight against her back.