Because A&B day work just fine because it seperates the classes and puts order in the class. It helps kids learn better, more time to do homework! And no one wants to see the same teacher and be in the same class everyday. More homework less days, causes them to Fail a class for that nine weeks. Which can cause to fail a semester, and more people in summer school and that's time to relax . An what college wants to look at a student who failed a semester.