Two years ago I taped a bunch of Chinese flash cards (Chinese character on one side, English meaning on the other) to my living room wall (shown above). I’ll study them in off moments, I thought. I didn’t. It was embarrassing when guests pointed to a card and said, “What’s that?” But not embarrassing enough.

A few weeks ago, I can’t remember why, I decided to test myself: how many do I know? About 20%. I’ll try to learn more, I thought. I was astonished how fast I learned the rest. It took little time and almost no effort. I didn’t need “study sessions”. I glanced at the array now and then, looked for cards I didn’t know yet, and flipped them to find out the answer. After a few days I knew all of them.