Buy well-fitting children shoes

Check out this article from The College of Podiatry

On average children’s feet grow at two sizes per year in the first four years of life and one size per year thereafter until growth is complete. However, a child’s foot may not grow for a considerable period of time and then grow several sizes in a relatively short period. To ensure that shoes still fit properly for length and width a trained shoe fitter should check them every eight weeks. You may do this more frequently if you are aware that they are actively growing in height....

http://www.scpod.org/help/guide-to-navigation/buy-well-fitting-shoes/