Hopefully your grandson's tube was a Schrader as well since "Presta" valves are smaller diameter and a rim with a hole drilled for Presta valves will usually not accept a larger Schrader valve. Some pumps have dual heads that accept both S and P valves but some only fit one of the two. Also if you have tubes with valves that are too short that you want to use you can get screw on extenders for both types. Schrader at any auto supply store and Presta at your bike shop.