It depends on what you mean by average. The median class size is well below twenty, but the mean is higher owing to a smaller number of very large classes with hundreds of students. It's possible to attend classes with as few as two students, and to choose very small classes for most of your degree.
370
The average class size at Howard University is 22 students.
The average class size for Yale University is about 1,318. The university generally takes about 1952 applicants a year.
The average class size at York's Keele Campus is 57 students.
20
11
As of 2011, the University of Houston has 39,820 students.
1,210
The University of Akron has a student to faculty ratio of around 20 to 1. The current average class size has around 18 students.
There are about 10 to 19 students in every class at princeton. :)
The average undergraduate student body at Princeton University is about 5,200. The graduating class size is usually between 1,200 and 1,300.
The average class size at Lubbock Christian University is around 17 students. This smaller class size allows for more personalized attention and interaction between students and faculty.