Monday, September 13, 2021

Game Promotion

One of my treats the last few years has be to teach a section of a course originated by Char Beckman, a senior seminar to make classroom math games. We dig into examples, come up with criteria to evaluate them, design and playtest.

One of the assignments is to make a video for an existing math game which has no video that they can find. Here are the videos from last Winter's designers - after too long a delay for which I apologize. If you're interested in the course, here's the course page.

Upcoming posts will feature their original games - with a lot of amazing work.  Are there games for which you would like to see a video? Leave a comment! I've got another group this fall.

Caleb Anderson - Safe or Sorry

Safe or Sorry is a push your luck dice game that emphasizes multiples. He explains, "I would like people to know of this game because of the simplicity of the game and that this game requires no skill. I think teachers should use this game for those who need to learn how to skip count by 5’s and if teachers are using probability. Safe or sorry has little to no strategy, so students don’t have advantages. This way, one student cannot be particularly good at the game because it is all based on chance. I think this game would be beneficial to students for those struggling with addition and also skip counting. Plus, since there is no strategy the game is more fair." So there's *no* strategy? I also like how this can be adapted to other multiples.

Original post: Safe or Sorry

Heather Anderson - Bad Calculators

Heather Anderson made this video to explain the one person web-based math game Bad Calculators. She says, "‘Bad Calculators’ is a web game that is a really useful tool for developing arithmetic ability. Because the game uses specific operations and moves per level, players use arithmetic creatively which allows them to have unique practice with their skills. I feel this game is easily distinguishable from some other math games because it has obstacles players must work past, but also because it gets increasingly more difficult the longer a player plays. Another aspect of this game that caught my attention was the fact that players are able to use their possible moves in any combination and/or order they choose (for most levels) because there is no penalty for the number of steps it takes to complete a level. This game has a lot of factors that non-math games have, which makes it appealing to players. Yet, it includes a lot of crucial, foundational ideas in mathematics which makes it a very impactful math game as well." Play the game at

Arianna Ayers - Make and Take

Arianna Ayers made this video for an upper elementary/middle school math game on mixed operations. (It's the first of several games from Nicholas Smith on this list. He's a GVSU grad who was - and still is - always willing to make and playtest games.) She says, "Make and Take is a great game that incorporates using number operations to create combinations of playing cards. This game is fun, engaging, and requires strategy. There’s also an element of surprise because the players do not know which cards they will be dealt from the deck. In addition, the rules are simple and easy to understand. All you need is a deck of playing cards and at least two people, and you’ve got a recipe for a fun game night!"

Original blogpost: Make and Take

Danielle Jurcich - Card Catch

Danielle Jurcich shows how to play Card Catch, a number and operation math game with playing cards, another made with Nicholas Smith. She says, "I chose to make a video about Card Catch because I really liked the idea that a teacher could simply have playing cards in their classroom and be able to play this game. The game can be played with between four and six people, so it is very interactive. Plus, the team aspect gets students to work together and even be able to devise a strategy for each card they lay down." Rules handout: Card Catch Handout

Cameron Morgan - Treasure Hunt

Cameron Morgan demonstrates Treasure Hunt, a Battleship style math game for integers. She says, "Treasure hunt is a math game that only requires the downloadable game sheet. This game allows students to use addition and subtraction while also practicing the number line model. Treasure Hunt is a great game to play in the classroom because it has many aspects that make a good game some examples being good interaction, good rules, and inertia. There is plenty of interaction between player 1 and 2 such that their moves against each other affect the game. The rules are not too easy or hard and if one was to think they were too easy there is also an accelerated version. The game does not last two long and would make students want to keep playing to see if they can win the next time. Overall this is a great game that helps students with addition or subtraction without being super overwhelming or competitive for them."

Gameboard is here: Treasure Hunt Gameboard (but it is easily played with pen and paper)

Olivia Sassanelli - Tug of War

Olivia Sassanelli started out making a video for a math game by me, but ended up making her own twist on it. She notes, "This game is a good game for younger students who are learning basic addition and subtraction of whole numbers (both positive and negative). For the content of this game, the students can focus on whether or not they want to add or subtract. This game also focuses on using strategy depending on which variation the students decide to play. This game is a super basic and simple game to play at the end of a lesson or to even play during class a few times. This game is quick to play so it works as a game students can play if there is time at the end of a lesson as well. The set up is very simple and the supplies are typically supplies you have laying around the classroom. Overall, this game has good content for the students with practicing basic addition and subtraction and also a super basic set up. I highly recommend this game because the feedback I received from students as well was very positive and the students generally enjoyed the game too!"

Original game: Tug of War (original) (Has a bit more interaction and back and forth.)

Kayla Shirah - Honeycomb

Kayla Shirah demonstrates Honeycomb, another Nick Smith math game collaboration on integer operations. She explains, "Honestly, reading the instructions I was a little confused. The visuals on the game instructions on what to do if you rolled a negative number was helpful but it was confusing to remember to flip the sign of the number you are multiplying by and by how ever many of the number you rolled. It made sense once I played the game with my fiance. With this being confusing at first to me as a college student, I thought well there isn’t a video on this game so I’ll make one. It had materials that I knew I had in my house, two different colored dice, a coin, the game board. Which this would be ideal for a student or teacher to play as well. I liked how the game wasn’t too long in playing time as well. I loved playing this game, it was fun and interactive for both players the whole time. It also had an element of catch up if a player rolls a high number due to chance. I thought it would be helpful to show an example of game play when you first start out because you can only add a number onto the board. As well as show an example of multiplying by an existing number on the board, since that is what I think the reader of the instructions needed clarity on. I also wanted to visually show that you can only multiply in a straight line if possible. This game is a great simple material math game that can be played many times by lots of students. This game gives students an opportunity to make choices during each turn even though they have the chance of rolling the dice as well. Overall, honeycomb is an awesome game to get students to remember how fun it is to use positive and negative numbers in addition and multiplication." Handout with rules and gameboard: Honeycomb Gameboard and Rules. Nick says about this one - "This is the game I'm most proud of. I'd love to see this developed as an app. My original intent was to make it a 3d stacking game where the tiles flip black/white."

Sunday, March 28, 2021

Playful Math Carnival 145

Welcome to the 145th edition of the Playful Math Carnival. Once known as the Math Teachers at Play Carnival, this edition follows the Denise Gaskins' (founder of this here carnival) blowout 144th Anniversary Edition, as night doth follow gentle day, and by that we were blown away.  

Sadly, there's nothing interesting about the pentagonal semiprime 145. Well, besides 145=1!+4!+5!. There are only four numbers for which that's true.  And it's the fourth number that's a sum of squares in two different ways. And it's a Leyland number, because 3^4+4^3=145. (I wonder what the next Leyland numbers before and after are?) And the 145th prime number is 829 and 145829 is prime and the largest prime factor of 145 is 1+4+5+8+2+9 and that 145 is congruent to 1 in mod 8, mod 2, and mod 9. But besides that...  there's practically nothing. (All these are from Pat Bellew's fun number site.) And 145 shows up in Matt Parker's melancoil. 145 degrees (F) makes something medium rare...  maybe that should be the goal for this edition?

Volvo 145. Ove approved.

Hop in the 145 and let's go! 

Books & Essays

Just before this month started I got to participate in a nifty mathzine fest from Becky Warren, Chris Nho and Ayliean. Technically February, it was after Denise's edition so I'm counting it. Several of the results are on the Public Math website, which has more besides. Also see the mathszine hashtag on Twitter.

That was my introduction to Ayliean, who had some thoughts on STEMinism.

Some of those zines inspired Sophia Wood for her first Fractal Kitty zine, on the Cantor Set.

Jim Propp was musing on division by zero. History, what ifs, new possible numbers...

Edmund Harriss has a new children's book out, HELLO NUMBERS! What Can You Do? and has been out supporting the release. Read more at Chalkdust's Math Book of the Year series. Also super curious about Eugenia Cheng's Molly and the Mathematical Mystery.

Speaking of playful math authors, RIP to Norton Juster, author of The Phantom Tollbooth and The Dot and the Line.


Sarah Carter reviewed the mathgame Proof positively.

James Cleveland posted his new linear graphing mathgame. Played it with my games seminar students and I think there's a lot of potential.

Simon Gregg and his learners were making variations on Snakes and Ladders.

Henry Segerman suggests this negatively curved sliding puzzle.

Excellent post at Play and PK on Listening.  Guest appearance from the always welcome Max Ray Riek in that post.

I've been making some GeoGebra for remote learning play. There's a measure division game, a fraction comparison game, a fraction addition/iteration/equivalence game and the classic Shut the Box.


Dana Ernst shared quilts his student Michelle Reagan made on the 5 groups of order 8.

Practically a quilt, Master of the Pattern Blocks, Hana Murray, made this amazing tiling replete with dodecagons. 

Robert Fathauer was interviewed on Math, Art and Tessellations. His new book is a masterwork.

Sophia is also in the middle of a 101 days of coding challenge, and shared her ecliptic ripples.

Paula Beardell Krieg had some practical advice for cutting curves by cutting straight.

I got to work on a fun project with my son studying art education, Yemeni squares

Wait There's More

I found this perusing old NCTM practitioner journals for fraction tasks and it sparked some interesting conversation. Like just how many solutions are there?

And it wasn't the only time 1/3 appeared in this third month, as I saw a nifty Roger Nelson proof with out words of an odd identity.

Iva Sallay is hosting the next Playful Math Carnival, 146. It's sure to be a treat, as she is a prodigious puzzle poster herself (take these Easter season Egg Puzzles, for example), and found several possibilities for this edition!

I enjoy putting these together, even though I am not regularly blogging myself. (Despite my best intentions...) One of the reasons I started blogging was to share and curate some of the cool things I was seeing from the amazing MTBoS, and it's still a good thing. If you're interested in hosting, just let Denise know.

NPR made a comic of this teacher's pandemic teaching story. (Less helpful, probably, McSweeney's suggestions for teacher self-care.) Hope you are taking care of you and yours, and getting vaccinated!

So long 145! Hope it was 5x5.

Sunday, December 13, 2020

Escape Dr. Latham's Laboratory

The final game from the 2020 math capstone GAMES class. Begun by Char Beckmann, I was thrilled to teach this course and will soon have my second group. Here's the final entry, an escape room. Ashly was committed early on to make an escape room and I am impressed at the work as well as the perseverance required to finish while student teaching during the pandemic under the conditions .

GUEST POST by Ashly Latham

Escape Dr Latham’s Laboratory is a game I created for my capstone project for MTH 496. When I first heard that we were creating a game I thought of the escape room me and my friends played before the class where we sat down and started talking about creating our game. This inspired me to create an escape-room inspired math game that allowed students to have fun while also doing math!

This game originally started as a fifth grade game but as I got into an accident and injured my hand, I had to postpone the idea. Finally, when I received enough function to get back to work I was a Teacher Assistant in a third grade class classroom. These third graders inspired me to adjust the game so they could play it. 

The puzzles students will complete in this game will focus mostly on multiplication skills as this is what my students were working on at the time I created this. There are ten different puzzles but some puzzles have two answers which allow students to only play six puzzles each play. 

To create this game I searched the internet for fun multiplication puzzles. This included literal puzzles but also some riddles. After I found enough puzzles for what I wanted, I began to construct the scene cards. These tell a story as students work from puzzle to puzzle. The hardest part was constructing the solution wheel so that it was hard for students to guess answers and each answer had a different code. This took me spending lots of time creating my own symbols.

When I tried it out with my third grade students, they LOVED it. I tested out the first couple puzzles and the students were constantly asking where the rest were. After finishing it, I had those same students try it. It took two 30 minute sessions to complete but they sacrificed their recess time just to finish it! They even want to do it again to find the other solutions! 

In the attachment for the game, all of the topics and standards are explained along with how to begin the game and set everything up. Though it’s in color, you can absolutely print it out in black in white. I hope you give it a try as it’s very fun and rewarding! Though carving out an hours time of your classroom might be hard, you could have students do one puzzle a day for a morning or ending activity for the day. 

Ashly's extensive materials and instructions, including for her supper cool solution wheel are here.

In addition, each capstone student picked a good math game to promote with a video. Ashly picked Michael Pershan's Baldermath.

Thursday, December 3, 2020

Fractions vs Decimals

 From the things you forgot you wrote file...

Fractions vs. Decimals

The Battle of the Century

Ringside Announcer (RA): Welcome ladies and gentlemen to the Battle of the Century:  Fractions vs. Decimals!

Old Man Fractions has been king of the hill for so long he can remember the pharaohs.  But relative new-comer decimals has been rocketing through the ranks past previous contenders like Mixed Numbers and Percents, buoyed by the rise of science and handheld technology.  Tonight they settle the issue once and for all, mano a mano.

Color Commentator (CC):  That’s right, Jim.  And they have both clearly prepared.  Fractions has developed his upper body so much he looks positively improper.  Decimals has emphasized speed work, and is awfully quick to the point.  Hey, looks like they’re ready to start.


RA:  They come out swinging!  Fractions looks like his strategy is to corner decimals and work his weaker visual representations.  Oh there’s a pie model and a fraction strip combo!  Decimals finally lands a 100 grid haymaker and gets back out to the center of the ring.

CC:  Looks like that speed work is paying off, Jim.  Decimals is coldly calculating without having to hit any special menu buttons on the calc, if you know what I mean.

RA:  Not really, Howard, but I’m used to it.  Oh!  Decimal made a rounding error and Fractions lands an uppercut.  

CC:  That’s exactly the answer, Kid Decimals!

RA:  The traditionalists are out of their seats, cheering on Fractions.  Even the French are into it!

CC:  He’s certainly got that je ne sais quoi, eh, Jim?

RA:  Huh?  Back to the action, Fractions is pressing his advantage.  But decimals sees an opportunity and – oh! The referee calls time!

CC:  I don’t think it was intentional, but that was definitely below the vinculum.

RA:  The referee gives Decimals a warning and they’re back in.  Fractions still looks a little wobbly, and Decimals presses the advantage, really working over Fraction’s arcane and misunderstood algorithms.  

CC:  Invert and multiply that!  Whew!

RA:  Fractions gives a nice example of unit fraction multiplication and is back in the fight.  Oh, and lands a nice left hand on a complicated long-division problem.

CC:  Decimals looks like he doesn’t know if his point is going left or right, Jim.

RA:  It’s back and forth at this point folks.  Fractions simplifies nicely, and catches Decimals a good one.  Decimals lands a nice easy comparison, but Fractions hits a unit confusion counter-punch.  

CC:  That’s half of something, alright.  

RA:  Then Decimals comes right back with a repeating combination!  Oh, and a non-terminating, non-repeating wallop!  Fractions has no answer for that.

CC:  Right in the Pi hole!  Practically transcendental ring work, Jim.

RA:  They’re really taking a beating out there.  Howard, I think the crowd’s getting confused about what’s important here.

CC:  I think you’re right, Jim, there’s kind of a baffled silence.   Not that unusual at a rational battle like this one, though!


RA:  That’s time.  The fighters move to their corners.  The judges communicate their decision to the ref.  It’s pretty close on my scorecard, Howard.  What do you think?

CC:  Did you double check your answer, Jim?  Nothing would surprise me –

RA:  The ref is ready and brings both fighter’s to the center of the ring.… he pulls up both fighter’s hands!  It’s a draw!

CC:  The judges have called them equivalent!  Oh the equality!  Looks like we’re in for a rematch.

Wednesday, October 28, 2020

Zoom Chat

 I'm teaching fully remote this year and have been struggling with many aspects of it. Like one does.

My courses were scheduled online synchronous, hoping for ways to get these preservice teachers working with kids... which hasn't happened yet. We do an hour of synchronous time, then there's asynchronous time for the remaining, with a set assignment, and then homework for a time, usually with a fair amount of choice. Reading (NCTM journals, teacher blogs, ...) , video, problems, etc.

Today my class was pretty quiet. We do Zoom, using Jamboard for an interactive whiteboard. Often there are problems or discussions that start in breakout groups, randomized every few weeks, then come back for whole group discussion. Today, on our last day of trigonometry, we were tackling identities. I tried something new, which was going old school. We stayed whole group, I did an example, and then asked them to work individually and contribute. 

I usually start out with a Jamboard data prompt, sometimes my question and sometimes theirs. (I share these pretty frequently on Twitter.) Today was their question, and I tried having a parallel chat, where I asked them 'what's the scariest math problem or course?'

Tough call for me. The original Halloween, Hocus Pocus... and if you include monster themes, Young Frankenstein, Abbott and Costello Meet..., Universal monster movies... how do you pick? I will ask people to comment or explain, which hopefully gets some mics on and conversation started.

The chat was an effort to make sure they had that window open and were using it. 

triple integration using integration by parts
Triple integrals
calc 3 
Integrals with no foreseeable solution
MTH350 [modern algebra]
Calc 2
Calc 2
Scariest math problem/course…
MTH 350
I don't like logarithms. I didn't like Calc 3, but I had a hard time visualizing 3d problems. 
Combing multiple antiderivative rules to solve one problem
calc 2
I loved calc 2, but didn't like calc 3 as much. Maybe it was the teacher I had

Not everybody, but good participation. And, whoa, integration. Would not have called that.

The visual prompt was my favorite trigonometry diagram.

We talked a bit about the history, the mistranslation of sine, and a recurring theme for this unit, the connections between geometry and algebra.

We then looked at just one section together to get at the similar triangles we would be using. 

We started with the triangle in the center. I shared how I learned from a student in the long ago to pull them apart and reorient them. We worked through three questions, where each time I left them more to fill in in the proportion. They had a minute to think by themselves, then we discussed. But only two students were willing to take the mic and share what they're thinking.

So I asked them in the chat publicly to share how comfortable they were with these kind of problems, 0 = don't know how to start, 5 = confident they could solve them. I also asked them to privately message me a word about their participation. We've been using WAIT - Why Am I Talking or Why Aren't I Talking (from Jennifer White's great Desmos norm activity) as a framework for this.

Sorted (public): 


3  3  3  3  3  3
4  4  4  4  4  4
5  5

Timeline (private):

  • Wishing I was on fall break
  • I think I am confused on the proportions. I'm not seeing where to get those. 
  • I guess I’m not uncomfortable participating in discussion, but I didn’t, and haven’t been lately, because I am really burnt out and need to just focus on listening
  • I am at home and can’t really turn on my mic
  • I'm just confused about why we are talking about sin, cos, and tan as side lengths, and not ratios of the sides.
  • honestly I am fine with talking sometimes I knew my answer was wrong however but after switching the triangles around I really understood it
  • I found these problems kind of confusing. I was listening to the others to see if I could understand it from there and that did help.
  • Trig for me has always been a hard subject, it took me a lot longer to realize how all 3 triangles are related and then create the ratios
  • I feel ok with talking, but there are times where I would say something ang you're talking but I can't raise my hand, I'm not sure how. So I never get to say my thought.
  • I was not completely understanding the triangles
  • I felt like I could follow along well enough, but couldn't really piece it together. I'm still half asleep, I'm not a morning person
  • Very busy week with other classes and I’m trying to keep up with them too
  • I've always had a hard time with trigonometry so I don't have a lot of confidence in answering those types of questions in front of class
  • I could follow what was happening and what was being discussed, but I was struggling to answer the questions and explain the thinking behind them. But after they were explained, they make sense
  • I would have felt comfortable speaking aloud because I understand this material 
  • I don’t like talking in front of the whole group because I’m afraid I’m going to be wrong. This stuff is sort of confusing, and I’m not terribly confident in my answer.
  • I wanted to observe what other students come up with and have others the opportunity to do trig

So much to think about here. I said we'll discuss it on Monday (next class). I want to stress (again again) how we are looking for thinking and questions, not correct answers. About how they need to practice doing what they will want from their students. About their relatively privileged position (successful students, math majors, etc.) and empathy for their future learners. About how hard teaching is, but worthwhile. About how I'm trying to figure out this new teaching medium and that's hard. About how much I appreciate their honesty and honestly want to hear their thinking.

Genuine question: what would you want to discuss about this with novice teachers?

Class then went on to discuss a different diagram in their breakout groups, with mixed success. Here's a group that got more than typical written down about it. I also did a slide as a worked example for them to see afterward.

So that's my story! How are you creating opportunities for engagement or cultivating discussion in remote teaching? In the chat, or message me privately. Wait, is this mic on?

Tuesday, July 14, 2020

Moving Patterns

Anyone familiar with this blog will know I have three main avocations in math and math ed: using tech for visualizing, combining math with art, and doing math through playing games. And things that combine any two of those things, wowee.

But here is one! Malke Rosenfeld has developed a math game that builds off of her depth of experience exploring math through movement, in particular dance. I had the amazing experience of being in her workshop first for my first Twitter Math Camp. My dance partner was the phenomenal Melynee Negelee, who is the moving force behind #elemmathchat. That was where I first got to meet Glenn Waddell and Edmund Harriss in person, too.

Since then, I've brought in Malke to work with my preservice teachers, present at the university, asked her to speak at our local conference Math in Action. I always get more out of each time, and the preservice teachers are very positive. I've tried to incorporate some of what I've learned from her by including embodied mathematics in all levels of courses and even trying a (non-professional dancer) version of the Math in Your Feet work with preservice teachers and kids.

The game is a learning game that develops your understanding of the possible moves and combinations as you play. There's a lot of rich mathematics to recognize and do as you problem solve, recognize and develop patterns, see transformations in three dimensions and look for and create symmetry. She has put so much work and development into the ideas behind the game and the look and play of the cards as well. For myself, knowing a lot of the math already, it still is engaging as you try to get your body to do that, and there was plenty of math to think about. Kids and college learners have deep insights and good connections.

Find out more at Malke's game site: or at the kickstarter And I love how Malke has set it up so that schools get a copy of the game when you get a copy.

Bonus #mathcomic in honor of Moving Patterns.

Everybody dance now!

Wednesday, May 20, 2020

Playful Mathematics Carnival 138

Welcome to the Playful Mathematics Carnival 138, the edition with its choice of theme song? (Techno or punk. I vote for the Misfits, I guess.)  

I was frankly a bit surprised at how interesting 138 is. 138 is a sphenic number(the product of three distinct primes from the Greek for "wedge shaped"), but is special among the sphenics for being the smallest product of 3 primes, such that in base 10, the third prime is a concatenation of the other two: (2)(3)(23). What is the next such special sphenic? (Some of the pictures here were made with some Brent Yorgey inspired GeoGebra or David Mrugala inspired GeoGebra.

138 is the sum of four consecutive primes (29 + 31 + 37 + 41); which is the previous and the next? 138 the sum of 2 successive primes; which? And not only is 138 the average of twin primes, it is a number such that 6 times 138, is the center of twin primes, 827 and 829. Is there another number like that?

I had never heard of Ulam numbers: a(1) = 1; a(2) = 2; for n>2, a(n) = least number > a(n-1) which is a unique sum of two distinct earlier terms in exactly one way. 138 is an Ulam number... what are the two terms which make it? Which is the first counting number not an Ulam number?

Obviously, this month's edition is in the time of social distancing. So it has produced some stand out creative home mathematics. Nikky Case made an interactive explanation how the epidemiological models work. Eva Thanheiser wrote a post about numeracy in the pandemic time. Here's an applet if you're trying to model a gathering... or a classroom?

Denise Gaskins, the initiator of this here carnival here, has a post for those new to it on how to homeschool math and Peter Rowlett at the Aperiodical wrote about playful math at home

Whilst there you might check out the 2020 Lockdown Math-Off, with some really accessible entries this year. And you can submit until they run out of entries or they're allowed outside.

Lily Cole
Math Art
Evelyn Lamb collected some of my favoritest math away from school resources. Cited there, Annie Perkins' #mathartchallenge (Twitter) is maybe my favorite thing ever. Here's the home (blog) for it. Brings together so many amazing projects from so many amazing artists and mathers. Like, Paula Krieg's origami firework on Day 53. Several have compulsed me to try to make things, like the Hitomezahi stitching from Day 14. Annie's going until she hits the magical 100! 

Clarissa Grandi's #Maydala challenge has filled Twitter with lovely images.
Clarissa herself
Janet Annetts

Japleen Kaur

Miss Bowkett

Paula Krieg

More mathy math
Henri Picciotto put together two amazing posts looking at wallpaper symmetries, and a catalog of pattern block Wallpaper symmetries; part I and part II. (Challenging, I think, because the blocks themselves are so symmetric.)

Luca Moroni pointed out Raffaella Mulas' self-illustrated article on Wild Mathematics. Quick mind bending read or just ponder the pictures.

ImagePaula Krieg also pointed out this classic puzzle that Dr Olsen points out can be made from origami.

Karen Campe covers a wide variety of puzzles, from the jigsaw to the Catriona Shearer.

Simon Gregg started this thread about duck tiles, which continue to delight. He also published a sweet book on pattern blocks. If you just want the pdf, let them know and they'll donate the book to a local school.

Pat Bellew (of On This Day in Math) chases a white rabbit, running around My avorite Theorem and the arithmetic triangle. (I'm hoping that catches on over Pascal's someday.)

Justin Time
Not sure how to categorize this, ironically, but Justin Aion's post on alignment charts and teaching is amazing.

Denise Gaskins, the initiator of this here carnival here, has a War meta-post with variations from preK through HS. I use several of these in a variety of classes. 

Sam Shah collected many activities and games you can do over videochat with a class. Nia (@ihartnia) put together a Google doc of quarantine games: 

Dan Finkel updated his Horseshoe Math game with a theme song!

Ben Orlin shared 6 intriguing pen and paper strategy games.

Carole Fullerton covers a silly game called Penguins. Kind of a computation bingo variant.

Kent Haines' kids are chips off the ol' block, having invented Math Ball.

My retired colleague Char Beckmann developed many math games with our students and they've all been collected here. Materials, instructions, and video demonstrations.

This past semester I got to supervise three preservice elementary teacher/math majors in their senior projects to make math games. Char Beckmann's project! Our emphasis was to make instructional games that you could play with materials on hand or with minimal printing. Sam Bosma made a fun Guess Who variant for multiplication and division, Multiply Who. Maggie Eisenga developed Choose Your Path, a hit the target game with playing cards with some very cool discrete elements. Grace Gay increased the math content in Quixx, a dice game with some subtle strategy, to make Rolie Polie Operation Olie. All are upper elementary-middle school, and have how-to-play videos.

In Memoriam 
Playful math lost two giants recently and I wanted to close with some remembrances.

John Conway was an all time great mathematician. Siobhan Roberts, his biographer, wrote two pieces for the New York Times, a memorial and a personal memoir. (Her book is excellent.) Sunil Singh said if you watch just one bit of Conway talking, watch this. James Propp is an unabashed groupie. Ivars Petersen shared a couple recollections. Pat Bellew remembered his impossible knot and Quanta covered its solution. Matt Baker remembered some of his lesser known results. I can't pick a favorite, but some of the most fun I've had with students is the rational tangle.

Don Steward was an amazingly creative and generous middle school maths teacher in England. Brilliant problem poser and visualizer and entirely low tech. Colleen Young wrote about some of her favorites. Jo Morgan wrote about her collaborations. Steven Cavadino shares an irrational triangle. Many people shared their favorite Don Steward task on Twitter. He did a sweet analysis of a Keith Richardson-Jones drawing that inspired some GeoGebra from me. Don's local paper wrote up a note on his importance to the community, and of course you should check the blog of the man himself, which he made arrangements to keep available and free.

On that somber note, we close the carnival.  Be safe, be kind! 

But on your way out... maybe check last month's Playful Math at Life Through a Mathematician’s Eyes or their recent post, 10 math movie recommendations, and look for next month's at Math Mama Writes, or check her post about Pythagorean Triples for an online math circle.  The carnival's homepage is at the site of Denise Gaskins, the initiator of this here carnival here. Contact her for your chance to host!