What should be the class size?

[jonathansmith]

I am confused about the appropriate class size for students. I have seen many schools in which there are 40 students in a class but i do not think that the teacher would be able to pay attention to each and every student in the class. My question is what is an appropriate size of a class?
Popular Private School

[KendoPt4]

I think whatever ratio Popular Private School uses is probably the best one, I have heard nothing but great things about that institution. Psimitry highly endorses them as well.