With only a few minutes to go before my class came in, in addition to weaving my tale of a distance formula - Pythagorean Theorem analogy, I had a list of technical bullet points that I had to mention. I had seen students get stuck on these details, and to keep the lesson going smoothly, I wanted to short-circuit any misunderstandings.
As I was feeling anxious that I might forget one of my talking points, I realized that the advice I was giving my students was exactly the advice I needed to hear myself. Taken separately, any list is difficult and cumbersome to memorize, but lists become easy when they tell a story or help jog a strong memory. No one can remember a jumble of mathematical symbols, but each part of the distance formula tells part of the story of using the Pythagorean Theorem: we subtract the x-coordinates and the y-coordinates – that’s measuring the legs of our right triangle; we square each of these numbers and add the results – that’s using the Pythagorean Theorem; finally, we square root the answer – that’s just putting the last step of using the Pythagorean Theorem, finding c, into the formula. This is the clarity and direction that I hope to bring to my lessons.