Thimble is my favorite code site for learning how to experience the web!
How I Use It
Start with a project that someone else has created and learn. Then create something using Thimble, share it and teach someone else. What didn't work was that it did seem a bit tough to create from scratch when knowledge wasn't there so having kids do multiple projects or even learn through code academy was good before they could create using Thimble. It's a great platform either way.