This site has lots of grammar lessons and online practice activities. It's not a great stand-alone Web site, but it could be useful as a fun technological supplement to an in-class activity. The site does contain some fun puzzles and poems as well.
This extensive collection of the fables of La Fontaine includes the complete French text, as well as English and even Latin translations. Some fables include audio versions. Fables are a great way to introduce young learners to French, as they are well-known and feature easy-to-understand morals.