Mewn ysgolion bach, ychydig iawn o ddisgyblion, os o gwbl, fydd yn cyfrannu at y mesurau perfformiad a gaiff eu defnyddio i gyfrif y bandiau. Golyga hynny y bydd mesurau perfformiad ysgolion bach yn amrywio'n aruthrol o flwyddyn i flwyddyn, a gallai'r newid fod mor eithafol â 100% a 0% mewn unrhyw flwyddyn, gan ddibynnu ar allu 1 disgybl neu griw bach o ddisgyblion.
When schools are small there will be very few pupils, or even sometimes no pupils, who contribute to the performance measures which are used in the calculation of banding. This means that a small school’s performance measures will fluctuate markedly from year to year, and this could be as extreme as 100% or 0% in any year, depending on the capability of 1 or a handful of pupils.