There have been a lot of studies that show completing simple crosswrds and word games are an ideal way for people to learn English.
There's a wonderful site called <a href="http://www.youplay.com">YouPlay</a>, which has brand new crossword puzzles every day, and they're free. There are also a lot of word games, and number games if you prefer those too.
I hope this helps you in your teaching, as it's certainly helped my students over the years.
- Teaching resources
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