Celebrating math with festivals
Math is irresistible and fascinating, and it turns out, there’s a bigger community for it, too. We host a LoveMath! festival for girls in the fall and a spring festival for all. If you’re less familiar with the recreational math world, you’re in for a treat! We solve logic puzzles and brain teasers (think magic squares and tangrams), work together in escape rooms, and make mathy art.
LoveMath! Festival for Girls
Saturday, November 7, 2026
Spring math festival
Saturday, April 10, 2027
The Pickleball Problem
One day, Hedgie Wedgie went to the Proof Open, a pickleball contest held over 48 consecutive days. He liked watching the match so much that he invited his twin, Wedgie Hedgie, to join him the next day. They had such a good time that they each invited one more hedgehog to watch with them the following day. Each successive day, the number of hedgehogs continued to double—this was the hottest invite in town!
On the 16th day, Hedgie noticed that their numbers were starting to fill a small but not insignificant corner of the arena. Being the curious and clever hedgehog he is, he wondered how long it would take for hedgehogs to completely fill the arena. After doing a lot of thinking, he accurately calculated it would take exactly the number of days the contest was going to last. (What coincidence!)
On which day was the arena half full of hedgehogs?
Think about the problem backwards from day 48.
Bjorn Impersonates a Hedgehog
Bjorn is a lovable shark who really wants to be a hedgehog, so he puts on a pretty convincing costume, and attends a small summit of hedgehogs. Once everyone arrives, they look at each with suspicion: Only 26 hedgehogs were invited, and 27 were in attendance. Clearly, there was an imposter!
After some murmur and argument, Hedgie Wedgie declares he has a way to find the imposter: As everyone knows, all hedgehogs weigh exactly the same, and Bjorn, after making sure he weighed that precise figure, had forgotten that the costume added weight. Hedgie pulls out a simple balance scale and figures he'll catch the imposter. But there is a note on the scale: It is only accurate for the first three weighings. After that, it's a bust.
How does Hedgie Wedgie find the imposter?
What if there were only three hedgehogs and one weighing?
Bjorn Loves Boba
Bjorn makes a boba run every day, and over the years, the boba vendor has taken a liking to him. One day, she tells Bjorn: “I’m going to retire soon, and I’m gifting my boba shop to the person who can solve a puzzle.” Bjorn is excited: Not only does he love boba, but he loves puzzles.
The boba vendor says “Let’s say I made 1,000 boba drinks for a big party. One of the boba drinks has more sugar than the others. I’ll give you 10 sugar detection machines that can pinpoint which drink has the added sugar. The machine takes 1 hour to run its test and produce a result, and you can mix any number of drinks, in any amount, to form larger batches. Anyone who can solve my puzzle in 1 hour will inherit my boba shop.”
Bjorn thinks about it, and then says, “Give me the keys to the shop!” How did he do it?
Label each boba drink with a number from 1 to 1,000, and convert those numbers into a 10-digit binary equivalent.
Camping out with math
Camp Lemma is our one-week summer day program for rising 4th-9th graders who love math. Our campers learn, create, and play in a mathematically-rich environment, surrounded by like-minded peers and guided by a fairly friendly staff of teachers and camp counselors (who are themselves Proofniks).
Activities allow students to explore a variety of mathematical topics outside the standard middle school and high school curriculum. From polytopes and secret codes to probability paradoxes, we give students a sense of just how varied and fun math can be.
More info for Summer 2027 coming soon!
Developing math teachers
We host the San Francisco Math Teachers’ Circle throughout the academic year. Think of it as professional development + a mini math festival all rolled into one. Meetings are held monthly on Saturday mornings (typically 10:30am–1pm) for anyone interested in exploring accessible, exciting topics in mathematics.
For more information, visit the SFMTC’s website here.
In math we trust
The math world is pretty connected, and we like providing a space where it can happen. Our school, board, teachers, and students have all collaborated with like-minded organizations, whether that is the Julia Robertson Math FestivalandGathering 4 Gardner, summer camps like MathPath and Mathcamp, and contests both national and local, such as Omega and the Bay Area Math Olympiad.
Most recently, we hosted the Bay Area Math Out Loud Olympiad, or BAMOLO, a competition modeled on the UW Math Olympiad where participants walk judges through how they solved problems. This special olympiad started nearly 20 years ago in Seattle, and 2026 was the first year it took place outside of Washington.
“Volunteering at math festivals has always been really special for me, because my first experience with Proof was at a math festival.”
“I thought it was cool to meet new people at a festival with similar interests to me.”
“Helping others grow is really great”
“Watching kids thrive, make friends, and develop their interest in math at Camp Lemma is especially rewarding”
“I enjoyed getting to meet younger kids who loved math and enjoyed being able to talk to them over a game of chess.”
“Seeing the moment when something suddenly makes sense is always so special.”
Mailing out math and more
Proofniks like to jump into the mix and pursue their own outreach. They’ve staffed tables at Gathering for Gardner, attended plenty of Maker Faires, and have served as residential counselors at summer math programs. Last year, two seniors won a grant to put together a curiosity box of fun math problems to mail out. It was a huge undertaking, and a group of returning Proofniks are going to carry that project forward.
Catalina, 11th grade
Favorite math class
Number Theory
If not math, then
Art. I’m in a sewing class this year.
Find me at break...
making stickers.
Outside of school
I’m building a robot.
Rhea, 11th grade
Favorite math class
Number Theory
If not math, then
Art. I’m in a sewing class this year.
Find me at break...
making stickers.
Outside of school
I’m building a robot.
Linda Green, PhD
What do the kids call you?
Linda
What brought you to Proof from UNC—Chapel Hill?
I heard about Proof School when it was first getting started. I liked the idea of being able to lead math festivals and build math sculptures as part of my job, and Proof’s small size and quirkiness appealed to me.
You’re clued into the recreational math community. What drives you to do this sort of outreach?
Outreach activities can foster kids' natural curiosity and joy, and reframe math as exploration and play. I love sharing my favorite puzzles and activities with others and seeing their excitement.
