Thimble is my favorite code site for learning how to experience the web!
Community Review for Mozilla Thimble
My Take
I loved the entire collection of Mozilla tools starting with teach.mozilla.org because it doesn't only focus on coding, which is text based javascript, but focuses on learning how the web works and being cognizant of important things like copyright. I love that it is self-guided and is about creating something that can be recreated. Again, for beginners, I do recommend tackling several projects before jumping in blindly but I do recommend eventually jumping in as Thimble has proved that doing so is the most effective way to learn.
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.