The 2-4-6 Puzzle teaches an invaluable lesson about inductive reasoning, confirmation bias, and how “wrong” answers lead to deeper knowledge. It can be adapted with different rules for endless play options and difficulties. Also see Josh Golden’s writeup of Eleusis Express for a card game version of the game, perfect to play with standard cards, SET cards, or Tiny Polka …

## Subtracting Reverses

This extraordinary lesson combines base ten subtraction practice with an irresistible mystery. A pattern slowly reveals itself as the class compiles data.

## Cuisenaire Rods for K/1/2

Topics: Addition, subtraction, measurement, skip counting Materials: See specific lessons Recommended Grade: K, 1, 2 Common Core: K.CC.B.4, K.CC.B.5, K.OA.A.1, K.OA.A.2, K.OA.A.3, 1.OA.A.1, 1.OA.A.2, 1.OA.D.7 Overview This series of lessons is meant to introduce Cuisenaire rods in a creative, engaging way, and see how Cuisenaire rods can illuminate and motivate addition, subtraction, and measurement. Why We Love Cuisenaire Rods Cuisenaire rods are …

## Billiard Ball Problem

The Billiard Ball Problem is a beautiful exploration of a situation both natural and novel. Great for problem solving, with connections to ratio and proportion. Also check out this Billiard Ball simulator on Scratch.

## Rectangles with Whole Area and Fractional Sides

Math concepts: Fraction/decimal multiplication, area model of multiplication Materials: Paper and pencil Tags: 5.NBT.B.7, 5.NF.4, 5.NF.6, I love the question at the heart of this lesson—it’s simple but counter intuitive. This is a perfect way to let kids look for something without The Launch Consider a rectangle. If the side lengths are whole numbers, then so is the area. Do …

## What’s the biggest rectangle?

Math concepts: Area, perimeter, number patterns Materials: Graph paper, pencil Tags: 3.MD.7.a-b, 4.OA2, 4.OA.3, 4.OA.5, 4.OA.5, 5.OA.3, MP1, MP2, MP3, MP5, MP6, MP7. Of all the rectangles with a given perimeter, which one has the largest area? This simple question launches a fascinating exploration. The Launch Remind students of the definition of area and perimeter. Then pose the following question: …

## Volume Menu

Topics: Volume, surface area, multiplication, number patterns, estimation, unit conversion Materials: Menu worksheets, cubes, perspective paper (optional), rulers, pencil andpaper Common Core: 5. NBT.5, 5.MD.1, 5.MD.3, 5.MD.4, 5.MD.5.a-c, MP1, MP2, MP3, MP5, MP6, MP7, MP8 Using a Menu The idea of using a “menu” to teach math is simple: with minimal time spent on introduction, you make available a wide array of …

## Magic Triangles

Topics: Addition, Subtraction, Logic Materials: Pencil and paper Recommended Grades: 1, 2, 3 Common Core: K.OA.A.2, K.OA.A.4, 1.OA.A.2, 1.OA.B.3, 1.OA.B.4, 1.OA.C.5,1.OA.C.6, 1.OA.D.8, 2.OA.B.2, MP1. Magic Triangles are a simple addition/missing addend problem that creates opportunities for higher level thinking. Kids must place the numbers 1 through 6 on the outside of a triangle to make the numbers on each side sum to …

## The Hundred Chart Game

Topics: addition, subtraction, strategy Materials: Two types of tokens (gems & pawns), hundreds chart Recommended Grades: 1, 2, 3 Common Core: 1.NBT.C.4, 1.NBT.C.5, 1.NBT.C.6, C2.NBT.B.5 Add and subtract 10s and 1s to pick up the tokens on the hundreds chart. Why We Love The Hundred Chart Game This game delivers tons of addition and subtraction practice in a way kids love. …

## Flower Petal Puzzles

Topics: addition, subtraction, logic Materials: Worksheets, pencil and scratch paper Recommended Grades: 1, 2, 3 Common Core: 1.OA.A.2, 1.OA.C.6, 1.OA.D.8, 2.OA.B.2, MP1, MP7 Put each number in a “petal” so each line of three numbers in a row has the same sum. Why We Love Flower Petal Puzzles This is a simple but thought-provoking puzzle. It’s a great way to …