I have a friend who is a high school teacher, and I was shocked to learn how they evaluate him. (No idea how true this is for other schools). They compare the

I have a friend who is a high school teacher, and I was shocked to learn how they evaluate him. (No idea how true this is for other schools). They compare the standardized test scores of this years group of students with those of last year's. If these students do better than those, he must have improved, and if they do worse, he must have slacked. Now, he'll have between 20-100 students each year. Any teacher will tell you that the variation between one year's group of students and the next is considerable. (indeed, among my teacher friends I've learned it's a major point of gossip - not individual students, but the collective lot) This seems insane to me. Why not compare this years students with THOSE SAME STUDENTS' SCORES from last year? Or find something else less likely to be so "swingy".