Grand Rapids, MI
7/3/2010
Here’s what you should know about the corner of Bostwick and Crescent in downtown GR: I had my first algebra class in a building on that corner. On the third floor, I had Algebra 1 with Mrs. Molloy. I am sure that was the first time I spent any quality time with the quadratic formula.
The building where I went to middle and high school is no longer standing. Luckily, it was replaced with the science building of the local community college. I think someone going to or from that building will appreciate seeing the quadratic formula in the context of the graph of a parabola.
Good ol’ calculus will confirm that vertex (the lowest (or highest) point) of a parabola will lie on the line x = –b/(2a). From there, you just have to add or subtract some stuff to find where the parabola crosses the x-axis (of course, sometimes you have to use your imagination to “see” the crossings). This is why we have the “plus or minus” in the quadratic formula. Parabolas are symmetrical.
Any calculus students out there, I invite you to tell us quickly how to confirm the business about the vertex.
Footpath Math: Chalk it up to a math geek 
What a lovely freak you are, Eric Mann! And I mean that in a totally good way, one freak to another. I just spent an hour taking pictures of rocks, so… you feel me?
I feel you. So far, my chalk drawings have had a component of seeing and showing bits we don’t normally see. I have a quite similar experience when I look at your photos.
I’m looking forward to spotting some of these in downtown Austin.
I’ll be watching.
Me, too!