And then you were to give me another avocado.” Another circle, like a face drawn by a seven-year-old.

“Well, if I have one” - the arrow draws a rudimentary circle - “let’s call that an avocado. Have I not mastered this? Why can’t I look away? “Now I think you already know how to do this but I’ll show you a way of doing this in case you don’t have this memorized or you haven’t already mastered this.” ONE.” The arrow descends, leaving in its wake a jagged, aliased line - the hasty chicken scratch of a Microsoft Paint scribble. “Let’s say that I start with an old classic. Hopefully by the end of this presentation it will seem… basic.”Ī low-resolution arrow stutters into the frame. “I know what you’re thinking: ‘Sal, addition doesn’t seem so basic to me.’ Well, I apologize. I half expect it to offer me a menu of options: Press two for advanced suuub-traction. The voice is jaunty, conversational, ridiculously awake. I stare into the empty black frame of the YouTube video - literally a blank digital slate. “Welcome to the presentation on basic addition.”

Salman Khan, Founder of the Khan Academy.

Advanced algebra khan academy