Learn better with this simple tip for improving recall

The Scientific American article Getting It Wrong: Surprising Tips on How to Learn explains how to improve our recall in learning:

People remember things better, longer, if they are given very challenging tests on the material, tests at which they are bound to fail. In a series of experiments, they showed that if students make an unsuccessful attempt to retrieve information before receiving an answer, they remember the information better than in a control condition in which they simply study the information. Trying and failing to retrieve the answer is actually helpful to learning....By challenging ourselves to retrieve or generate answers we can improve our recall.