Re-reading is inefficient. Here are 8 tips for studying smarter.

"One good technique to use instead is to read once, then quiz yourself, either using questions at the back of a textbook chapter, or making up your own questions. Retrieving that information is what actually produces more robust learning and memory.

"And even when you can't retrieve it - when you get the questions wrong - it gives you an accurate diagnostic on what you don't know, and this tells you what you should go back and study. This helps guide your studying more effectively.

"Asking questions also helps you understand more deeply. Say you're learning about world history, and how ancient Rome and Greece were trading partners. Stop and ask yourself why they became trading partners. Why did they become shipbuilders, and learn to navigate the seas? It doesn't always have to be why - you can ask how, or what.

"Anything that creates active learning - generating understanding on your own - is very effective in retention. It basically means the learner needs to become more involved and more engaged, and less passive."

"Flashcards are another good way of doing this. And one key to using them is actually re-testing yourself on the ones you got right.

"A lot of students will answer the question on a flashcard, and take it out of the deck if they get it right. But it turns out this isn't a good idea - repeating the act of memory retrieval is important. Studies show that keeping the correct item in the deck and encountering it again is useful. You might want to practice the incorrect items a little more, but repeated exposure to the ones you get right is important too.