A credit hour represents 50 minutes of lecture time for each week of a semester. Most schools that work on the semester system have 15 weeks of instruction followed by a week of final exams. Most college-level courses include three sessions weekly for three semester hours.
At the college level, professors expect students to prepare for their classes. The class sessions represent one-third of the total time the course requires for successful completion. Students should spend two hours of preparation time for each session. The preparation includes reading the text and completing homework for the course.
Some schools use the quarter system instead of the semester system. Quarters are significantly shorter than semesters; for example, a quarter hour is equivalent to two-thirds of a semester hour.