In the issue, the speaker suggests that students should suspect all knowledge taught by their teachers. It is likely to reasonable at first glance. However, after I exam the opinion of the speaker carefully, I consider that the advice is too absolute about the problem about studying, as discussed below.
At the beginning, I agree with the speaker of contention that skepticism is a useful to help students learn more active. Teaching is a process which needs interaction between students and teachers. Without skepticism from students, teachers would not acquaint students well through studying actions, and they should not improve their teaching effects better to suit to students. On the other hand, without skepticism of students own, they should not learn and master knowledge they are taught well enough to use them in the future. Hence, I think that the speaker's broad opinion, considering students should question what they are taught, is correct and persuasive.
However, it is not proper for the speaker to suggest that whatever being taught should be doubted by students. I will provide some evidences to support my opinion. First, too much skepticism will baffle the development of science and society. As we all know, whatever is taught in classroom already becomes axiom what has been proved by a lot of scientists and experts from one generation to another and from historical era to nowadays. Too much skepticism will lead to waste of budgets and human resources. It is not a proper way about studying and researching. Second, if students focus more sprits on doubting what they are taught, they will have little time to understand knowledge and create achievements in the future. Even if Newton, the most famous and great scientist, had once declaimed that his successes were based on achievements of his form scientists. Let us imagine that Newton would not get so many inventions and creations, if he only focuses on suspecting on what he was taught in lessons, because he would have little time to think about solving methods about scientific problems.
Therefore, I suggest that students should choose the best proper ways to resolve problems about skepticism, due to studying period of their own. For example, primary students should pay attention on teachers' lessons with more understanding and less suspecting. This kind of learning means could help them use less time to accept more fresh but basic knowledge. However, students should bring a certain and purposive skepticism to what they are taught. In this higher and more advanced periods of study, students should not accepting knowledge passively, which is useless for their constantly develop on researching. With suspecting about whatever they study, students could think about problems by their own methods, and create more advanced or fresher achievements than fore scientists. Without skepticism, people would not know that Earth is round and we are not in the center of the world.
In summary, the speaker should edit his opinion a little to make it more rational. Skepticism is a crucial period during studying of students, but students should balance the suspecting and learning in order to using lest time and energy to gain most achievements.