Playschool is a British word for a playgroup: a place where very young children (often around two to four) go for a few hours to play with other children, not to sit at desks and study. There may be songs, sand, paint, and a snack, and a grown-up watching, but it is not ‘real school’ in the sense of reading lessons and tests. Parents in Britain still say playschool; in the US you are more likely to hear preschool or playgroup. The -school in the word is a bit grand for what actually happens — that is the joke and the trap. In writing it is usually one word.