No matter which strategies learners employ to absorb and retain knowledge, the process should be active, difficult, and effortful. The authors emphasize this point throughout the book as they discuss different tenets of effective learning, acknowledging its counterintuitive nature. People tend to think that if the learning process is a struggle, they must not be doing it correctly or productively. Learning that feels easier seems more productive—but according to research, “when the mind has to work, learning sticks better” (43).

The authors cite studies that demonstrate this principle in different contexts. In Chapter 2, the authors advocate testing as an effective learning tool. Testing is useful when integrated into a larger process of information synthesis and recall. When tests (in any form, ranging from self-testing with flashcards to in-class quizzes) are spaced out rather than experienced in quick succession, learners have to work harder to retrieve information they might have started to forget. This scenario is especially beneficial for long-term learning. 

Chapter 4 further elaborates on the benefits of “desirable difficulties,” a psychological term comprising “short-term impediments that make for stronger learning” in the long-term (68). Difficulty of this sort aids both cognitive learning and motor skills (like those utilized in sports).