Crosswords are great for making kids think, and to think differently (Jeopardy style). You give them the answer, they have to come up with the “question”. I like crosswords if I know I’m going to be absent, or for kids who always seem to finish their work early.
There are tons of crossword generators, but some of them really stink. This one is particular is multi-language friendly, and is very customizable.
It is well-explained, and the least tech savvy person can use it.