Flash cards are an incredibly useful tool for helping you memorize anything. You should use them whether you’re learning to code, studying for an exam, or even doing some public speaking. You can jot facts and details onto the cards and use them as prompts. Or with double-sided cards you can write a question on one side and the answer on the other, and you’ve got a ready-made pop quiz to test yourself at any time. But you don’t need to have an actual set of cards and a pen; your phone can do the job just as well.