wsj

Newsmart uses articles from the Wall Street Journal to promote learning English as a second language. It’s a slick site, and it’s free.

Users pick an article, and then there are color-coded portions in it for vocabulary and grammar. Click on it, and you are given a question about the in-context grammar or vocabulary issue. You then accumulate points and badges.

I’m adding it to The Best Websites For Intermediate Readers.