An effect of presentation on improving levels of understanding is discussed and reported. In order to improve understanding levels of students, traditional lectures and experimets are not sufficient. We consider that a learned knowledge will be refined through presentation to other person. The understanding levels will be also improved through discussing with listener of the presentation. We assigned our students a presentation task at open campus. They presented about Fleming’ s left hand rule to guests. In this paper, it is evaluated that the understanding levels of students is improved through presentation.