A blurb from Today's People:
When your child gets fitted for their first pair, it’s about more than just having enough room for their toes. First, the foot is measured for length and width. Next he’ll try the shoe on, then a list of things are checked. “The width, instep, and flex point—where the sole of the shoe is most easily bent—are all important measurements,” says Linda Goulet, president of Panda Shoes, a Canadian children’s footwear retail chain. As for length, given that your child’s likely going to need two to three pairs of shoes each year until growth slows down, it can be tempting to buy shoes a size bigger. Goulet recommends you don’t.
“It’s the same as it would be for adults: Are you going to be comfortable walking in shoes that are too big? No. Plus, if the shoe is too big, the flex point will be in the wrong place and won’t support or protect the foot properly.” Ill-fitting shoes may lead to slips, trips, and falls, which can cause ankle damage. Take your time in the store so you can watch how your child walks in each pair. “If they’re on tippytoes or not walking properly, something’s hurting. Have patience in the process,” says Stern.