Diben y system gategoreiddio yw pennu pa gefnogaeth sydd ei hangen ar ysgolion i wella. Mae categoreiddio'n cynnig dull cyfannol o wella ysgolion, sy'n caniatáu i'r consortia addysg rhanbarthol ystyried cyd-destun ysgol wrth ddyfarnu ar ei hunanwerthusiad a'i chapasiti i wella.
The purpose of the categorisation system is to identify what support our schools need to improve. It offers a holistic approach to school improvement, which allows the regional education consortia to take the context of the school into account when determining a judgement on the school`s self-evaluation and capacity to improve.