Ima kind of moving to khan academy now too.
BUT.
I still use code.org somewhat. For example, I made a cuboid renderer on khanacademy and put the code in CDO.
Oh and I DIDNT use WEBGL for this. I used trigonometry.
function rotateZaxis(theta) {
var sintheta = sin(theta);
var costheta = cos(theta):
… more boring code…
}