The elasticity of these socks is very weak. They're good socks for temporary use, but they won't last more than a month for your kid who has to wear a uniform every day. Comfortable fit, just need more elasticity.
Pros
My 5 year old is a giant BUT I got the 8 year old package and they are still cozy. Everything else about them is great.
Cons
May not meet dress code requirements for some schools