Indian engineer Avrind Gupta has long been teaching children the basics of electricity, magnetism, optics, and even engineering by letting them make and play with toys and devices they make out of common low-cost materials. To spread the word beyond India, he has taken to YouTube in a big way by posting simple, easy-to-follow directions for building hundreds of different toys in 15 different languages.
One of Gupta’s favorites, which was invented by friends who are the parents of a blind child, is the touching slate. It lets users “write” with a spool of yarn on a panel covered with Velcro. Children with or without eyesight can create shapes and figures, then recognize them by feel.