Examination is to test the knowledge acquired from what the students have been taught over a period of time. If examination will be a true test of knowledge,some factors need to be considered, the competency and qualifications of the teachers, tutors, lecturers...etc so as to ascertain if the students will be taught the required subjects with the required experience and Quality required . There is also need to consider the environment where pupils, students learn or are been taught, will a pupil learn comfortable learning sitting on the floor or in hot sun under the tree, will a student learn when taught by the lecturers in a jam packed class? If all and other conditions are meet including having a standard library with Books available for students to consult for further understanding of what is been taught and Laboratory , and the students are really drill by giving them constant continuous assessment tests and assignments, it will be discover that most of the students will perform excellently and above average. And then can i be able to agree that examination is the test of true knowledge, if not, our medial doctors will not be able to graduate and treat a patient and other, if the examination they write was not a true test of knowledge of what they are taught and practicals inclusive. Also other professions like engineering, Pilots...etc. all under go examination before graduating as a result of satisfying the examiners based on their knowledge.
I agree to a point. Yes written exams will test your knowledge to a point. But it is not an absolute test of knowledge. There is this thing called not testing well. I've seen people way smarter than me, well everyone is smarter than me, but this person is actually beyond book smart. But this person also cracks under pressure when taking the exams and would get average marks.