Acquiring an extensive vocabulary is one of the keys to success in learning a language. Many learners spend hours learning long lists of words or trying to memorize flashcards, which can be rather boring — and not always very effective. When doing a crossword, on the other hand, you are actively thinking about the language and using your brain to literally solve a puzzle. Research has shown that this engagement with the language helps the learning process, and it's certainly a more fun way to learn. But that's not all, it seems that crosswords may also be beneficial to your social, emotional, mental, and physical health!
In a British-style grid, there are a lot of black squares. Roughly half of the letters in each word are crossed over with another word (what's called "keyed" or "checked" in the industry). This is known as an alternate-letter grid — in general, every other letter in a word is checked. In an American-style grid, there are relatively few black squares, and every single letter in every word is crossed over by another word. The grid is fully "checked". So it's theoretically possible to solve a whole American crossword by only doing the Down clues, for example (not very pedagogical!) All my general crosswords follow the classic British model, but the thematic ones differ slightly inasmuch as they are not symmetrical (that would be virtually impossible). I've also used some two-letter words, which is not standard practice.
Absolutely. Although the focus is on learners of English as a second or foreign language, the crosswords could just as well be used with younger learners whose first language is English. And if you find The Times or Guardian crosswords a bit too difficult, then try Crossword English!
You can find lots of ideas for using crosswords in the classroom and tips on making your own crosswords in my PDF e-book 101 Thematic Crosswords for Learners of English.
Check out my blog (www.englishblog.com), where you should find just about everything you need.