Mae’n ofynnol i ysgolion ddarparu 5 niwrnod o Hyfforddiant Mewn Swydd (HMS) statudol ar gyfer athrawon ym mhob blwyddyn ysgol. Caiff yr ysgolion eu cau i ddisgyblion ar y diwrnodau hyn er mwyn i athrawon gymryd rhan mewn gweithgareddau hyfforddi yn rhan o’u datblygiad proffesiynol parhaus.
Schools are required to provide teachers with 5 statutory In-service Training (INSET) days during each school year. On these days schools are closed to pupils so that teachers may participate in training activities as part of their ongoing professional development.