PRODUCTIVITY PUZZLES. Interesting question at Econ Log. Does a smaller class size imply lower teacher productivity? What is the marginal product of additional dollars spent on addtional teachers, evaluated as improved student performance? By what standard "improved?" Perhaps there is a simpler approach. If there is a teacher "shortage," there is some combination of improved compensation and improved working conditions (a complex proposition: does that mean smaller classes, less mainstreaming of difficult students, more backbone in dealing with difficult students and the parents who enable them) at which the shortage disappears.