What size beds are in your kids' rooms?

All due respect, but I think you’re mistaken. My “twin” sheets fit a mattress which is more than half of a full mattress width, and the mattress they fit was likewise labeled a “twin” mattress, and fits on a “twin” bedframe.

TheInternational Mattress Sizes chart on wikipedia indicates that a single and a twin are the same size. There’s something smaller than a single/twin in the UK called a “mini single”, but even that is wider than half a double/full (UK: “small double”). ETA: A mini single is half of a UK sized King, is that what you were thinking of, perhaps?

Hallboy (15 and nearly 6 feet tall) has a double due to his size, but I’m thinking he’ll be in a queen before too long. (Heck, my bed is a double and I’d like to upgrade to a queen as well.) Our bedrooms are small–mine measures 12 x 11, and his is probably 10 x 11 or so. A queen size bed would be a tight fit, but he mostly just sleeps in his room (no computer, projects or toys or anything).