To proceed from primary to middle school, middle to high school or high school to college, national exams must be passed. Institutions of higher education include the University of Ouagadougou, The Polytechnic University of Bobo-Dioulasso, and the University of Koudougou, which is also a teacher training institution. There are some small private colleges in the capital city of Ouagadougou but these are affordable to only a small portion of the population.