alt Hacker NewsIt annoys me, though, that there's a prescribed method of estimation, which is hard to remember. I always used to get the "wrong" answer because I picked easier-to-add approximations, even though my estimates were generally both faster and closer. (To use your example, I'd have estimated 35 or 36: the sum of two small numbers, like 2 and 3, is normally about 5; and this sum is a little bit less than (1 + 2)×12 = 3×12.)
Yes, teaching and assessment of estimation can get quite dreadful. Wish I'd saved a video I saw years ago, intended as an exemplar of best practices in early primary, where it was clear neither teacher nor students had a clue, all the effort was around attempted signalling of the expected but misguided answers, and everyone was collaborating to pretend that understanding had occurred. Recording a class can be hard, but it was wild.