What's a good, straightforward crossword puzzle game for my iPad that doesn't try to be too fancy? I just want a good mental workout while I'm grading papers.

Well, after trying a few different crossword apps, I settled on Crossword Puzzle Redstone. Took me a few days to figure out all the features, and why do they hide the settings button there anyway? But once you get the hang of it, it's surprisingly intuitive. It's got a clean interface, which is important to me – I don't need a lot of bells and whistles. More importantly, it's got a huge library of puzzles, so I'm not constantly running out of content. My students actually showed me this trick to reveal a letter when I get stuck, but don't tell them I use it! It's like having a teaching assistant in your pocket, but for vocabulary. And best of all, it works offline. The school's Wi-Fi is about as reliable as a teenager's promise to do their homework, so that's a big plus. Even I could figure it out, and that's saying something.