### Hand-drawn visualization

*Visualization techniques have always been important in mathematics and its applications, and they are especially so nowadays as sophisticated computer graphics enhance our ability to interpret phenomena we could not imagine a generation ago. But you can only really appreciate what the computer is showing you if you've tried to render the curves and surfaces freehand. Almost all of my students get the hang of it well enough to draw a pretty good surface, and some display a particular talent for illustrating mathematical ideas.* - from The Best Homework Ever?

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