As an activity of one working group for the Good Practice program at Kumamoto University, we proposed a questionnaire survey on the degree in which students understand the uppermost points of importance in their classes in addition to the usual type of class questionnaire. Each class lists three uppermost points of importance which are essential for understanding the class content. The degree of understanding is classified into four levels: full, most, insufficient, and not at all understandings. Through the analysis of questionnaire replies, the degree of understanding for bachelor students in the Department of Engineering was discovered to be meaningfully affected by the degree of difficulty, the effectiveness of audiovisual aids, self-study time, and class attendance.