Let’s Retire #MTBoS

I’m not asking us to retire the #MTBoS (unabbreviated: the Math Twitterblogosphere) the collection of people, ideas, and relationships that has provided the most satisfying professional development and community of my life.

I’m asking us to stop referring to it as “the MTBoS” and to stop using the hashtag “#MTBoS” in online conversations.

That’s because this community is only as good as the people we invite into it. We currently represent only the tiniest fraction of the math teachers in the world, which means we (and I’d like to believe they also) are missing out.

That fraction will stay tiny so long as our name alienates people. And it alienates people.

People don’t know how to pronounce our name. Whenever I use it, I get tweets back asking me what I’m talking about. Whenever I invite new teachers to get on Twitter and search for “#MTBoS,” their confusion is plain at that seemingly random assortment of vowels and consonants, capitalized in seemingly random ways.

This morning I read a tweet from a science teacher named Andrew Morrison. I learned from Andrew that the physics teaching community hashtags their work “#iteachphysics.” I felt such a sense of invitation when I read that hashtag – “This is who we are and what we do. You should join us.” And then I felt envy.

We should be so inviting.

This community of ours has no leader. It has no high council. Each one of us has to be the change we want to see in it. I want to see a more inviting community, a community that doesn’t shroud its entrance behind a hedge or protect its door with a password.

So I’m going to stop referring to my participation in “the MTBoS” and instead talk about how much I love “Math Teacher Twitter.” I’m going to stop tweeting using “#MTBoS” and instead tweet using “#iteachmath.”

No one has to join me, and I absolutely won’t be offended if you don’t, but I hope you will, and I hope you at least understand why I’m doing this. I think this change is necessary for our growth and this is how I’ll try to be that change.

Reservations That I Had About This Proposal That I Don’t Anymore

“#iteachmath” is five more characters than “#MTBoS. That’s five fewer characters for my tweets!”

I accept that those five characters are the cost of a more inviting community.

Twitter users outside the United States will want to use “#iteachmaths.”

The MTBoS has a very, very tiny handful of community members outside the United States as it is. I think we can only improve from here. Me, I’m going to add both “#iteachmaths” and “#iteachmath” to the same column in Tweetdeck.

“MTBoS” includes blogs (the “B”) but “Math Teacher Twitter” just refers to Twitter.

“MTBoS” also fails to refer to Slack, Voxer, or any of the other ways teachers collaborate online. “Math Teacher Twitter” hints at all those ways. It doesn’t try to catalog them.

But I’m a coach / consultant / curriculum author / administrator. I don’t teach math so I’ll feel weird using “#iteachmath”.

Let’s not treat this hashtag like it’s a sworn statement in a court of law. It’s an invitation. It’s how we’ll gather community around a conversation. It doesn’t need to serve any higher purpose than that, and I think it’ll serve that purpose better than anything we have right now.

Featured Tweets

Justin’s tweet seems really, really important to me. Consider the perceived requirements for membership in the #MTBoS vs. #iteachmath.

#MTBoS: who knows, but a blood sample and credit verification is probably part of it.

#iteachmath: it’s right there in the hashtag. That’s it. No guessing. You’re invited.

Featured Comments

Angel Martinez:

I joined the community of online teachers this last year and attended the national conference. MTBoS felt like a secret society that I wished to be a part of but didn’t know how to get in.

Cathy Yenca:

… my honest-to-goodness first thought about being invited was, “Am I ‘in’ the #MTBoS ‘enough’ to speak about it with these other mathies who seem to be ‘in’ it ‘more’?


This makes me happy. For months when I first discovered #MTBoS, I had no idea what it stood for and felt so left out! And then I had no idea how to talk about it to others. (And usually resorted to “it’s basically math teacher twitter.”)

Pomegraphit & How Desmos Designs Activities

Eight years ago, this XKCD comic crossed my desk, then into my classes, onto my blog, and through my professional development workshops.

That single comic has put thousands of students in a position to encounter the power and delight of the coordinate plane. But I’ve never been happier with those experiences than I was when my team at Desmos partnered with the team at CPM to create a lesson we call Pomegraphit.

It’s yours to use.

Here is how Pomegraphit reflects some of the core design principles of the teaching team at Desmos.

Ask for informal analysis before formal analysis.

Flip open your textbook to the chapter that introduces the coordinate plane. I’ll wager $5 that the first coordinate plane students see includes a grid. Here’s the top Google result for “coordinate plane explanation” for example.

A gridded plane is the formal sibling of the gridless plane. The gridded plane allows for more power and precision, but a student’s earliest experience plotting two dimensions simultaneously shouldn’t involve precision or even numerical measurement. That can come later. Students should first ask themselves what it means when a point moves up, down, left, right, and, especially, diagonally.

So there isn’t a single numerical coordinate or gridline in Pomegraphit.

Delay feedback for reflection, especially during concept development activities.

It seemed impossible for us to offer students any automatic feedback here. After a student graphs her fruit, we have no way of telling her, “Your understanding of the coordinate plane is incomplete.” This is because there is no right way to place a fruit. Every answer could be correct. Maybe this student really thinks grapes are gross and difficult to eat. We can’t assume here.

So watch this! We first asked students to signal tastiness and difficulty using checkboxes, a more familiar representation.

Now we know the quadrants where we should find each student’s fruit. So when the student then graphs her fruit, on the next screen we don’t say, “Your opinions are wrong.” We say, “Your graph and your checkboxes disagree.”

Then it’s up to students to bring those two representations into alignment, bringing their understanding of both representations up to the same level.

Create objects that promote mathematical conversations between teachers and students.

Until now, it’s been impossible for me to have one particular conversation about the tasty-easy graph. It’s been impossible for me to ask one particular question about everyone’s graphs, because the answer has been scattered in pieces across everyone’s papers. But when all of your students are using networked devices using some of the best math edtech available, we can collect all of those answers and ask the question I’ve wanted to ask for years:

“What’s the most controversial fruit in the room? How can we find out?”

Is it the lemon?

Or is it the strawberry?

What will it be in your classes? Find out and let us know.

2017 Jun 16. Ben Orlin adds several different graphs of his own. Delete his objects and ask your students to choose and graph their own. Then show Ben’s.

This Is My Favorite Cell Phone Policy

Schools around the world are struggling to integrate modern technology like cell phones into existing instructional routines. Their stances towards that technology range from total proscription – no cell phones allowed from first bell to last – to unlimited usage. Both of those policies seem misguided to me for the same reason: they don’t offer students help, coaching, or feedback in the complex skills of focus and self-regulation.

Enter Tony Riehl’s cell phone policy, which I love for many reasons, not least of which because it isn’t exclusively a cell phone policy. It’s a distractions policy.

What Tony’s “distraction box” does very well:

  • It makes the positive statement that “we’re in class to work with as few distractions as possible.” It isn’t a negative statement about any particular distraction. Great mission statement.
  • Specifically, it doesn’t single out cell phones. The reality is that cell phones are only one kind of technology students will bring to school, and digital technology is only one distractor out of many. Tony notes that “these items have changed over time, but include fast food toys, bouncy balls, Rubik’s cubes, bobble heads, magic cards, and the hot items now are the fidget cubes and fidget spinners.”
  • It acknowledges differences between students. What distracts you might not distract me. My cell phone distracts my learning so it goes in the box. Your cell phone helps you learn so it stays on your desk.
  • It builds rather than erodes the relationship between teachers and students. Cell phone policies often encourage teachers to become detectives and students to learn to evade them. None of this does any good for the working relationship between teachers and students. Meanwhile, Tony describes a policy that has “changed the atmosphere of my room,” a policy in which students and teachers are mutually respected and mutually invested.

Read his post. Great, right? How would you build on his work?

2017 May 26. Okay, okay, we have a bunch of font critics in the comments thread!

Featured Tweet

This is a different approach. The cell phones are in jail. But I admire the incentive for parking your phone.

How I Welcome Newcomers to Online Teacher Professional Development (a/k/a the #MTBoS) and How You Can Too

Here is the promise:

There is a community of math educators that meets online at all hours of the day. They trade support and resources and many of the educators who meet there will tell you it is the most indispensable professional development they have ever experienced. If you lack support in your school or district, this community might actually get you through. I’m referring to the the Math Twitterblogosphere, or the #MTBoS, an abbreviation that is as unwieldy and charming as the community it names.

Here is the reality:

Where am I? Who are all these people? Is it rude to just say something to somebody? These conversations look interesting but do I just … jump in?

Here is an ugly bit of unexamined privilege:

Loads of people informed me immediately that, nope, Twitter only works that way if you already have lots of followers, if you’re already in the community, and that it also helps to belong to a demographic that is accustomed to being listened to all the time.

People informed me that their first leap into this teaching community was scary, that getting “shot down” was bad, but bad also was simply getting ignored.

I decided I didn’t want to ignore a tweet from a newcomer to the Math Twitterblogosphere. So about a month ago I wrote up the designs for a Chrome extension and hired a freelancer to build it. The extension highlights tweets from users that meet any criteria I choose.

Here is my “Welcome to the #MTBoS” rule. It highlights tweets from anyone with fewer than 100 tweets, people who are likely new in town, so I can make sure they hear from somebody.

The results have been a blast. I don’t break much of a sweat on these welcome wagon tweets. “Never stop tweeting” is my standard greeting, after a more personal remark. Other times I try to connect newcomers to the resources they’re after. Regardless, people are generally really excited to receive these quick tweets.

That’s someone whose day got made because this little Twitter extension made it easy for me to make sure she didn’t get ignored.

You can make someone’s day too. Loads of these newcomers aren’t following me. Many of them are looking for classroom teachers to follow. Many of them are looking for people who are only a couple of years ahead of them in their careers, not ten or twenty.

You’re welcome to install the same extension, without any warranty, and with only the most meager set of instructions. (If I start hearing that a bunch of you want to install it, I’ll give it a proper download page with a proper set of instructions. 2017 May 25: Updated with that page.)

Hey. Good work, everybody. People are writing dissertations about us. People from outside mathematics education are looking in at us as a model for professional community. This place is special. Let’s keep expanding it – its numbers, its representation, and its heart. This is one idea I had recently. What’s yours?

Featured Comment

Michael Pershan offers his work towards community building: comment on more blogs.

Mathematical Surprise

I gave a talk at the Wisconsin state math conference earlier this month and this woman was the best part.

I don’t know her name. I’ll call her Jan. Jan is about to testify to the power of surprise.

I asked the crowd to give me three numbers between 1 and 6, numbers you might get from a roll of the dice. They said 2, 3, and 5. Then I asked all of them to evaluate those numbers in this expression.

Most of the crowd started working on that task, but Jan didn’t. She laughed and said, “I teach second grade,” excusing herself.

I encouraged her to show off whatever she remembered from the last time she worked with expressions like this. She scribbled on the notebook in her lap and we managed to evaluate x = 2 in the time we had, but not 3 or 5.

I asked the crowd to call out the result for 2, 3, and 5. They called out 2, 6, and 20, one after the other.

Then I asked the crowd to evaluate those same three numbers in this expression.

Jan tossed her notepad on the desk, a reaction of “no way, no thank you” to the length of that expression. I decided not to press her at that exact moment, because I had a secret everyone in the crowd would come to understand at different times, Jan last of all and perhaps best of all.

I asked for their result for 2.


“Okay, what about 3?”


“Okay, that’s weird. What about 5?”


I played up my surprise, acting like I didn’t know all of those terms would simplify to 0.

That’s when I noticed Jan. Out of the corner of my eye, Jan straighted up in her chair and then picked up her notebook to sort out what just happened.

I wish I had a sharper vocabulary to describe this transformation, as well as more strategies for provoking it. By showing Jan a situation where order arose from apparent disorder, she felt something in the neighborhood of … cognitive conflict? Intellectual need? “Surprise” feels closest.

I don’t know all the words and I don’t know all the strategies, but I know there are few gifts a teacher can give a student more satisfying than helping her transform from “no way, no thank you” to “okay, let’s sort this out.”


  • I don’t think this experience has much to do with Jan’s growth mindset about herself, or mine about her, but I’m willing to be proven wrong. How was this experience distinct (or similar) to a mindset experience?
  • Think about the design of this activity, all of its different permutations, and how each one might have affected Jan. What if, for instance, I had given given the class those three numbers instead of soliciting them from the class? What if I had only solicited one number? What if all three numbers didn’t evaluate to the same number? How would these permutations have affected Jan’s interest in picking up her notebook?