A five-minute conversation sparked so much sidewalk math

I’ve been really into sidewalk math for a while. It started with me laying it down with students at school to doing it at local parks in the Bronx, where I live. All of this ballooned into my sharing it last August at TMCNYC as a My Favorites.

After I shared it at TMCNYC, Michael Pershan came up and asked me whether or not I had thought about sharing sidewalk math with a larger audience. Other than Twitter, I hadn’t. He mentioned that maybe I should, that it might be well received by the larger teaching community — specifically those at math ed conferences, like NCTM.

Michael and I spoke for a mere 5 minutes, but our conversation inspired me to write a post where I rethought who benefits math ed conferences. Need it only be the attendees? Can we math teachers leave something to a local community to engage with both during and after we leave their space? Can we leave the host city better than we found it mathematically? Though there are many ways to do this, I was thinking of hosting a session at conferences, gathering teachers, taking to the streets, and doing sidewalk math. It’s not going to change the world, but it could help move the needle a tad bit towards spreading math and including more people in conversations about math.

Last winter and spring, I began pitching my idea. I wanted to do sidewalk math at conferences. I didn’t know any better and didn’t really want to spend buckets of dollars traveling halfway across the country, so I proposed my idea to five local conferences. All but one was in NYC.

I guess Michael was right, there was a thirst for public displays of math. All of the conferences let me host a sidewalk math session. Yay!

The odds are pretty good that I’ll never be asked to present anything this much ever again, so now that it’s over, I want to bottle up some of my experiences over these last couple of months.


June 6, 2019: EdxEdNYCThis was the first one and by far the most nerve-racking. Having never have presented at a conference before, I was deathly scared about having an adequate amount of material for the time slot. Plus, because I built in time to actually going outside to do sidewalk math in the local neighborhood, if it rained, I didn’t know what the hell I was going to do. I was so paranoid that I literally checked the weather every few hours in the days leading up to the conference. In the end, it didn’t rain and the timing worked out really well. I had a couple of former colleagues in the session, so it was also great to able to share it with them. It’s a small detail, but I made an effort to stand outside the room and greet folks as they walked in. I was not only hoping to welcome everyone to the space, but also ease my nerves by connecting, however briefly, to each attendee individually. It really worked. I made a point to do this at all of the upcoming workshops, too.


July 10, 2019: Math for America Summer Think | This one felt the homiest to me. Also, these teachers were probably the most eager and able to do sidewalk math. There were about 20 people in the session, which was about half of the EdxEdNYC group. And as someone who has been part of MfA for several years, I knew more than a handful of the folks in the audience. There was even a couple of science teachers there, who so eloquently created some sidewalk science. All in all, we fanned out and chalked up the Flatiron district pretty good. There were definitely some sidewalk math problems put down that I pocketed for future use. Interestingly, I learned that the park rangers at Bryant Park are not fans of sidewalk chalk. Boo! Anyways, I was 2 for 2 on avoiding the rain.


August 5, 2019: Museum of Math MOVES Conference | Of the five sessions, this one was the most contingent on the weather. The session had no inside component. Thankfully, it didn’t rain! (Up to this point, I couldn’t believe the luck I was having. The rain gods were sparing me.) We met outside in front of the Museum of Math and went to town. The Museum of Math is across from Bryant Park, so I didn’t dare bring my chalk inside of the park for fear of a garden hose. I spent the good part of an hour mathing up the sidewalk around the park. I put down close to 20 pieces. Ironically, I talked about sidewalk math to more strangers than I did attendees. This was pretty cool in its own right. One of them even tweeted about one of the problems.


August 14, 2019: TMCNYC | This was where it all started! Bringing my chalk to BMCC in lower Manhattan was like coming home. The organizers managed to allot the session a full hour, which meant that we could take to the streets. There was a threat of rain during the afternoon, so Michael Pershan and I went out early and scouted for covered areas. Thankfully, it didn’t rain until the end of the day. I was now 4 for 4 and I was convinced that fate was on my side. I brought so much chalk that the sidewalk math continued into the second and third days of the conference. I mean these people brought it! I swear one of the teachers even had a makeshift lesson going on in front of her sidewalk math. On my last day, I went all in and created some bulletin board math at a local restaurant.


September 26, 2019: NCTM Regional Boston | This was the grand-daddy of them all. It was the last one of the sequence and by far the largest. I was uncertain about how many people would elect to come to the session, but there ended up being over 100 people jammed into a windowless room that was desperate for fresh air. On top of that, it was the last session of the day. Called a “Burst,” it was only 30 minutes, which was nice because I didn’t really have to worry about rain since we wouldn’t have time to go outside. This turned out to be great because right after the session, Boston was flooded with the heaviest rain I have ever seen in my life. I’m most proud of the fact that no one left the session while I was presenting. When it comes down to it, that’s all you can really ask for. I was also happy that I decided to give away several boxes of sidewalk chalk during the session that were used to create some sidewalk math in the days following my presentation. I wish I had thought of this for the earlier sessions I had during the summer. Who doesn’t like free stuff?



Sidewalk Math


Every time the weather gets turns favorable, I get inspired to grab some sidewalk chalk and do #sidewalkmath. It’s been a thing for me the last couple of years. It’s a great way to promote public displays of math (which we never see), get the general public thinking about math (which rarely happens informally), and work in some creativity in the process. I’ve been messing around with #sidewalkmath in the neighborhood where I live (here and here), and I’ve also had students take part the last couple of years.

With this in mind, last week I took the kiddos out to let them publicly showcase their mathematical prowess via the sidewalk. They were graphing trigonometric functions and the sidewalk was primed and ready to go. I numbered each slab in front of our school, paired them up, and gave them a trig function. I let them go. After they graphed their own equation, they had write the equation for another graph on the sidewalk.



I read somewhere that our school is located in the poorest congressional district in the U.S.  While the kids and I were out in front of our school sketching the functions, it hit me that the overwhelming majority of the people that walked by our math probably had clue what they were looking at. That’s disappointing for sure, but precisely why doing it was so important.