Erasure
When I was a kid, my mom used to have us memorize poems. She’d write the poem out on a whiteboard and we’d recite it a few times, then she’d start erasing a few words, have us recite it again, erase a few more, and so on. And it worked.
Turns out it’s super easy to do the same kind of thing in a web app. Here’s Erasure:
If you click on an erased word, it’ll briefly become visible again. (But of course you only want to do that if you’re really stuck.)
As usual, the code is on Github.