There is also significant variation in their size; the smallest is registered for a maximum of four learners and the largest a maximum of 1,500 learners.
Mae gwahaniaethau sylweddol o ran maint hefyd; mae'r ysgol leiaf wedi'i chofrestru ar gyfer hyd at bedwar dysgwr ac mae'r ysgol fwyaf wedi'i chofrestru ar gyfer hyd at 1,500 o ddysgwyr.