It's very easy for students to listen to lectures, read the textbook superficially, watch the professor work problems, read problem examples in textbooks, and say "That looks good—I get it." These may give only an "illusion of understanding". Students must continually put their understanding to the test [1].
Useful web pages:
Reference:
[1] Donald E. Simanek, Physics Course Survival Strategies Web-page,
available at http://www.lhup.edu/~dsimanek/survival.htm