I've benefited a great deal from the interactive exercises at Khan Academy, and I wish these folks the best. It's a huge undertaking to go beyond static illust

I've benefited a great deal from the interactive exercises at Khan Academy, and I wish these folks the best. It's a huge undertaking to go beyond static illustrations, to animations, to user-interactive immersive elements — and to make it all work smoothly across many platforms and devices. LOL, when I click on figure 2.3 I see "Firefox prevented this site from opening 21 pop-up windows." http://immersivemath.com/ila/ch02_vectors/ch02.html#fig_vec_translation http://immersivemath.com/ila/ch02_vectors/ch02.html#fig_vec_... Obviously a bug and not anything nefarious. Seeing this just makes me feel more grateful for their efforts.