Broaden the margins -- Basic theory. The story maker : the biology of memory ; The power of forgetting : a new theory of learning -- Retention. Breaking good habits : the effect of context on learning ; Spacing out : the advantage of breaking up study time ; The hidden value of ignorance : the many dimensions of testing -- Problem solving. The upside of distraction : the role of incubation in problem solving ; Quitting before you're ahead : the accumulating gifts of percolation ; Being mixed up : interleaving as an aid to comprehension -- Tapping the subconscious. Learning without thinking : harnessing perceptual discrimination ; You snooze, you win : the consolidating role of sleep -- The foraging brain -- Appendix. Eleven essential questions.