My son is having difficulty mastering the last 5 skills in the World of Math, two of which do not have videos. If better explanations aren't already included in the July update, then it would be awesome to include them the next time around.
The good news is this is the first time Khan's explanations came up short, even though he'd only had through Algebra II in school, in which he did poorly. He's gone from 32% last August to 99% now and feels he is well prepared for college calculus. The improvement in his confidence is amazing! Thank you!
Volumes of solids of known cross-section
Disk method (no video)
Washer method (no video)
Integrate & differentiate power series