It's a strategy of mixing up the type of problems you solve when you're testing yourself.

That way, the testing conditions are more similar to real life, where you first have to figure out what kind of problem you have on your hands and then solve it. 

You're experiencing fluency when you're reading something and it feels easy.

For example: you're at the airport and you're trying to remember which gate your flight is. You look at the terminal monitors — it's B44. You think to yourself that's easy to remember. Then you walk away, idly check your phone, and instantly forget where you're going.

When you're weaving in new threads into your pre-existing web of knowledge, you're elaborating.

The more you can explain the way your new learning relates to prior knowledge the more connections you create that will help you remember it later.

When people have the opportunity to reflect, they experience a boost in self-efficacy and self-confidence.

As a result, they put more effort into what they're doing and what they learn.