The country’s largest teachers union this week is discussing the idea of paying bonuses to teachers who improve test scores. The National Education Association is discussing “performance based pay”. It’s advertised both as way to reward and retain the best teachers and as a way to improve accountability to the public. Teachers are concerned they may be saddled with large classes or poorer students where it’s tougher to improve test scores. Brent Ghan with the Missouri State School Boards Association says teachers are looking for some consideration of classroom circumstances.