1.Spacing .

• Imagine you have to choose between practicing something ten times in a row vs. ten times spaced out (over hours or days).
• The first feels easier—you will perform better immediately after practice. The second is harder but results in more permanent memory.
• Yet students avoid spacing, in part, because it feels like it doesn’t work as well as cramming.

2. Variability .

• Say you’re learning tennis shots. Should you perfect your forehand swing before moving onto the backhand?
• Or mix both up at the same time? Intuition argues for mastering one thing before moving onto the next, but research suggests otherwise.
• Variable practice tends to result in better retention and transfer than blocked practice.

3. Testing .

• Should you re-read or do practice questions?
• Students overwhelmingly favor re-reading as a learning strategy.
• However, practice testing is one of the most effective learning methods that has been systematically studied, while re-reading is one of the worst.

The exact mechanisms behind the value of desirable difficulties are still being debated.

• Bjork argues that the benefits come from the difference between storage strength and retrieval strength in memory.
• In his theory, what we learn is never erased from our minds.
• Instead, we forget things as our ability to retrieve them becomes weaker through competition with other memories.

This theory says that successful access to hard-to-recall memory boosts retrieval strength more than if the memory was easier to access.

There’s another possible benefit to practice variability.

• When you mix practice between two similar ideas or concepts, you’re better able to notice the difference between the two.

L

• Math problems are often taught in a blocked fashion.
• You learn some problem type and do it repeatedly until you’re good at it.
• Then, you move onto a different type of problem and repeat the same process.

The issue with this blocked approach is that it doesn’t let you practice telling apart the different types of problems because, in each case, it’s obvious.