We use various inventions in our day to day life without even knowing the engineering behind it. This 1937 incredible explanation illustrating concepts of Differential shows that real knowledge is ability to explain complicated things in a simple way.
Starting with simple model to solve a problem and adding layers one after another to arrive at a complex result is an absolutely brilliant. This 9 minutes quality educational content video beats a semester of today’s shop class for sure. Practical, applied engineering at its finest.