San Francisco Math Circle – MathCircles.org

Fold & Cut

By:

Topic(s):

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Handouts, Photos & Videos, References, Virtual Tools

What shapes can result from the following fold-and-cut process?
Take a piece of paper.
Fold it flat.
Make one complete straight cut.
Unfold the pieces.
Are all shapes possible?

Wolves and Sheep

By:

Joshua Zucker, Spencer Bowen

Topic(s):

Combinatorics, Geometry, Problem Solving / General

Supporting Resources:

Facilitator Guides, Handouts, Photos & Videos, References, Virtual Tools

The rules are simple: you want to place the sheep on the board so that the wolves can’t eat them. A wolf can eat a sheep if it has a direct path to it – or is in same row, column, or diagonal as that sheep. Can you place all...

Mind Reading With Math

By:

Javier Haro, Spencer Bowen, Tyler Knapp

Topic(s):

Algebra / Arithmetic, Mathematical Games, Problem Solving / General

Supporting Resources:

Facilitator Guides, Handouts, Photos & Videos

For the Math Mind Reading Trick, you’ll need a volunteer who’s willing to have their mind read. The person performing the trick holds out the four cards and askes their volunteer to pick a number (whole numbers only, no fractions allowed!) between 1 and 15 and keep it a secret....

Queen’s Move

By:

David Klein, Spencer Bowen

Topic(s):

Combinatorics, Geometry, Mathematical Games, Number Theory, Problem Solving / General

Supporting Resources:

Facilitator Guides, Handouts, Photos & Videos, References

Students will explore a game between two players moving a chess Queen from place to place on a square grid. The Queen may move any number of spaces to the left, any number of spaces downward, and any number of spaces on the downward-left pointing diagonal. Each player takes turns...

Bubbling Cauldrons

By:

David Klein, Gord Hamilton, Spencer Bowen

Topic(s):

Algebra / Arithmetic, Mathematical Modeling, Problem Solving / General

Supporting Resources:

Facilitator Guides, Handouts, Photos & Videos, References, Virtual Tools

Place our numbers into the cauldrons in ascending order – you can choose which cauldron each one goes in. However, if two numbers in one cauldron add up to a third number in that same cauldron, they bubble up and cause an explosion! This means that all the numbers, leave...

Monty Hall Problem

By:

David Klein, Spencer Bowen

Topic(s):

Mathematical Games, Probability and Statistics

Supporting Resources:

Facilitator Guides, Handouts

A prize is hidden behind one of three doors. You choose the door where you think the prize is hidden. But before the door is opened, one of the other 2 remaining doors is opened to reveal no prize. You can choose to keep the door you chose earlier or...

Humans, Zombies, & Other Problems Crossing the River

By:

David Klein, Javier Haro, Spencer Bowen

Topic(s):

Mathematical Modeling, Problem Solving / General

Supporting Resources:

Facilitator Guides, Photos & Videos, Virtual Tools

A town faces an epidemic of zombies! Luckily, the virus has just started to spread and the infected are able to stave off their hunger for human brains… for now. In fact, they’re willing to work alongside the remaining humans to help them get across a river to safety. Can...

Puppies & Kittens

By:

Spencer Bowen

Topic(s):

Mathematical Games, Problem Solving / General

Supporting Resources:

Facilitator Guides, Photos & Videos, References

A local animal shelter has a puppies and kittens available for adoption that you just happen to be itching to own! In this week’s “paw-some” activity, two players begin with a certain number of animals to choose from and take turns adopting animals. The player to adopt the last animal...

Skyscrapers

By:

Nancy Blachman, Peter Liljedahl

Topic(s):

Combinatorics, Geometry, Problem Solving / General

Supporting Resources:

Facilitator Guides, Handouts, Photos & Videos, References, Virtual Tools

Skyscrapers come in so many different sizes! Sometimes you can’t see small skyscrapers if tall ones are in front of them. Using clues about how many skyscrapers you can see from each side you look at them, can you figure out the layout of the entire city?

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