What’s In My Brain: H vs Arrow

Two columns. One is an example, one isn’t. Can you figure out the hidden rule before the big reveal?

What’s In My Brain: Pentagon vs Pentagon

We’re looking at regular vs irregular polygons.

Letters With Symmetry

Let’s group letters by their symmetry, then create symmetrical words, and then symmetrical sentences!

Crossing Every Bridge Exactly Once (aka Eulerian Paths)

How can you cross each bridge in this city exactly once?

Math Curiosity: Magic Triangles

Can you make each side of this triangle add up to 9 using the digits 1-6?

Geometry Image: Esplanade Theaters

What odd and interesting shapes can your students find in this geometric image?

How Many Will There Be? Chip Off The Block

Give kids a taste of a sequence, let them build an understanding, and then see how far their predictions can take them.

How Many Will There Be? Earthworm

Give kids a taste of a sequence, let them build an understanding, and then see how far their predictions can take them.

How Many Will There Be? Courtyard

Give kids a taste of a sequence, let them build an understanding, and then see how far their predictions can take them.

How Many Will There Be? Checkerboard

Give kids a taste of a sequence, let them build an understanding, and then see how far their predictions can take them.

How Many Will There Be? Crosses

Give kids a taste of a sequence, let them build an understanding, and then see how far their predictions can take them.

How Many Will There Be? Squares in Squares

Give kids a taste of a sequence, let them build an understanding, and then see how far their predictions can take them.

What’s the Pattern? Fraction Addition

Can your students figure out how to add fractions by looking for a pattern?

Find The Pattern: Multiply Fractions

What if you set the stage for students to discover how to multiply fractions?

Olympics: Medals by Population

Do big countries always have the most medals? Which smaller countries rank surprisingly high in the Olympics?

Fizz Buzz: A Counting and Divisibility Game

Ready for a tricky counting and divisibility game?

How Many Will There Be? Pyramids

Give kids a taste of a sequence, let them build an understanding, and then see how far their predictions can take them.

How Many Will There Be? Sliced Circles

Give kids a taste of a sequence, let them build an understanding, and then see how far their predictions can take them.

How Many Will There Be? Xs and Os

Give kids a taste of a sequence, let them build an understanding, and then see how far their predictions can take them.

How Many Will There Be? Desks

Give kids a taste of a sequence, let them build an understanding, and then see how far their predictions can take them.

How Many Will There Be? Stairs

Give kids a taste of a sequence, let them build an understanding, and then see how far their predictions can take them.

How Many Will There Be? Flowers

These flowers sure are getting bigger faster! How large will they be in step 10? What about step 50?

How Many Will There Be? Triangles Within Triangles

A triangle splits and splits and splits again. How many will there be in step 20?

Math Curiosity: Klauber’s Triangle

In 1932, a leading authority on rattlesnakes, Laurence Klauber, discovered a startling pattern within a triangle of primes.

Math Curiosity: Ulam Spiral

What if we make a huge spiral of numbers and then highlight only the primes? Well, a bunch of weird patterns show up!

Math Curiosity: A Pattern Packed Triangle

Pascal’s pattern-packed triangle is a potent puzzle for pupils to ponder.

Math Curiosity: Goldbach’s Conjecture

Can any even number be written as the sum of two primes? Goldbach thought so, but we haven’t proven it… yet!

Create Your Own Operation

The commutative and associative properties are a whole lot more interesting when you apply them to a mathematical operation that you created!

Parentheses: How big of a change can they make!?

Two tiny parentheses. One expression. How big of a change can they make? Bigger than you think.

What’s In My Brain: Trapezoids or Not?

Which are trapezoids and which are not?

Same Perimeter, Different Area For Rectangles

Can two rectangles have the same perimeter but… different areas!?

Exponents – How Low Can They Go?

Using exponent patterns, can students predict what the 0th power will be?

Calculators, Patterns, and Multiplying By Decimals

Before teaching students the procedure for multiplying with decimals, how much can they intuitively glean from a structured play session with calculators?

Rounding Numbers (But Not To 10)

What could we possibly do to make rounding more interesting for students who already get it? In this series, students consider how they might round to values other than “the nearest 10.” How, for example, do we round to the nearest 9? 7? 15?

Math Curiosity: Four Squares

Every positive integer can be written as the sum of (at most) four perfect squares!

Math Curiosity: Magic Squares

Imagine a 3×3 square in which every row, column, and diagonal have the same sum. That’s a magic square!

Math Curiosity: The Coloring Problem

No video gets me more email from students! How few colors can you use to color in any map so that no two, neighboring regions are the same color?

The Angles of a Triangle

Why tell a kid the rules of a triangle when they can discover them!?

Math Curiosity: Odds & Squares

Why does the sum of the first 5 odds also equal 5 squared?

Math Curiosity: Waring’s Conjecture

So, can you write every odd (greater than 3) as the sum of three primes?

Math Curiosity: Primes and Squares

Can any perfect square be written as the sum of two primes?

Math Curiosity: Legendre’s Conjecture

It seems like there’s always a prime number between two perfect squares… but is this always the case!?

Math Curiosity: Finding Primes

Prime numbers are unpredictable! How can we possibly find them all? An Ancient Greek mathematician found one way!

Math Curiosity: Twin Primes

What do you call two prime numbers who are very close together?

Math Curiosity: Palindromic Number Conjecture

Using this one weird trick, it seems that you can turn any number into a palindrome!

The Game of 100

Who can get to 100 first in this simple, but delightful, math game?

Math Curiosity: Collatz Conjecture

The Collatz Conjecture: start with any number and get to 1 using just two rules. It seems to always work…