Visit www.codecademy.com, a site devoted to teaching code to all of us. The HTML & CSS course takes seven hours and already has 4.5 million students enrolled. The app’s free and was one of “10 Best Apps for Students” listed in the September issue of Family Circle magazine.
Another good free app: Khan Academy offers instruction in everything from simple math to quantum physics. The other eight from Family circle include some free, or with low fees. Especially of interest are Solar Walk and Mindsnacks U.S. Geography.