The use of black ink instead of soap is a teaching tools that is wonderfully clear, simple, convincing, easy to remember, quick to learn, strikingly different from other perfectly accurate videos. In fact, the motions are the same, the language isn’t English, yet the substitution of black ink makes the video a must see. The content is important, but as a teacher, it’s fascinating to see how someone figured out the potential problem of something that wasn’t broken, and fixed it by zeroing in on the vital lesson conveyed with the perfect tool (ink). Thus the saying, “if it ain’t broke don’t fix it,” was soundly debunked