Helpful Links

Chesskid.com is a great website offering both paid and free membership that will allow students to play online with other kids.  There are also interactive lessons and videos (Paid membership allows unlimited access)

Chess.com is the leading online chess playing site in the US.  It is very similar to Chesskid however the website is not exclusively catered to kids.  Chess.com offers similar instructional content to Chesskid (Again paid membership allows unlimited access) but with fewer cartoons and is a bit more serious overall.  It is recommended for more advanced players looking for a greater challenge and is safe website as well. (However, Parents might wish to personalize their student's privacy and security settings for their account before allowing their student to use the website unsupervised)

Lichess.org is the international version of Chess.com, with the added benefit of all the content being available for free.  Chess.com might offer a small amount of additional challenge overall but Lichess.org also features high level competition from some of the top players in the world.  It is the website Coach Simon personally prefers; however, he does tend to alternate between the two platforms frequently. Try the "Learn" tab for some quality instructive and practice content.

Chesstempo.com, like lichess.org, is also available for free.  It is mostly just a puzzle website designed to help students practice and learn important tactics and patterns.  The puzzles are randomly assigned to the student and are based on the students' performance rating.  Basically, the more puzzles answered correctly the higher the student's rating climbs and the harder the puzzles become and vice versa.  You can find these puzzles under "Chess Tactics" included in the "Training" dropdown menu. This puzzle feature is available on the other three listed websites, however only lichess.org offers unlimited puzzles without a paid membership.