The paragraph is followed by an incomplete phrase or sentence which summarizes the main idea of the paragraph. Choose the missing words of the phrase or sentence.

One aspect of American education too seldom challenged is the lecture system. Professors continue to lecture and students to take notes much as they did in the thirteenth century, when books were so scarce and expensive that few students could own them. The time is long overdue for us to abandon the lecture system and turn to methods that really work.
Lecture system needs to be（）