## Counterexamples

Topics: logic, deduction, mathematical argument, communication Materials: None Recommended Grades: K, 1, 2, 3, 4, 5, 6, 7, 8 Common Core: Variable, but especially MP3 Proving the teacher wrong. Rigorously. Why We Love Counterexamples Every kid loves to prove the teacher wrong. With Counterexamples, they get to do this in a productive way, and learn appropriate mathematical skepticism and communication …

3

## Blockout

Topics: Multiplication, area, strategy, addition. Materials: Crayons, Blockout game sheet Recommended Grades: 3, 4 Common Core: 3.OA.A.1, 3.OA.C.7, 3.MD.C.6, 3.MD.C.7 Roll the dice and shade in a rectangle. How can you claim the most space on the board? For 2-4 players. Why We Love Blockout This is one of those rare games that reinforces both the skill of multiplication and the …

2

## Multiplication Table Sums

Topics: Multiplication, summation, patterns and structure Materials: Multiplication table, pencil and paper Grade: 4, 5, 6 Common Core: 4.OA.1, 4.OA.3, 4.OA.5, 4.NBT.5, 5.OA.2, 5.OA.3, 6.RP.1, 6.EE.1,  MP1, MP2, MP3, MP6, MP7, MP8. This is a great puzzle for kids who have some comfort with multiplication but still need to deepen their understanding. It gets them looking at the multiplication table …

## Square Building

Topics: Area, multiplication, number patterns , geometry Grade: 3, 4, 5 Materials: Square tiles, graph paper Common Core: 3.MD.5, 3.MD.6, 3.MD.7, 4.OA.1, 4.NBT.5, 4.MD.3, 5.NBT.5,  MP1, MP2, MP3, MP5, MP6, MP7, MP8 This lesson is truly foundational. It connects central ideas of arithmetic and geometry, and advances from concrete to pictorial to abstract. It will prove to be a simple analogy …

## 1-2 Nim

Topics: logic, patterns, addition, counting, subtraction, divisibility and remainders (optional) Materials: Counters (tiles, beans, pennies, etc.) or paper and pencil Recommended Grades: K, 1, 2, 3, 4 Common Core: K.CC.A.2, K.CC.B.4, K.CC.B.5, K.OA.A.1, K.OA.A.2, K.OA.A.5, 1.OA.B.4, 1.OA.C.5, 2.OA.B.2, 3.OA.D.9, 3.OA.A.2, 3.OA.A.3, 4.OA.C.5, MP1, MP2, MP3, MP5, MP7, MP8 You can take one or two counters from the pile. How do …

2

## Don’t Break the Bank!

How to Play Everyone makes a diagram like this on their paper: Whole Class Game: The teacher (or a student) rolls the die. Whatever number it lands on, everyone enters it in one of the nine spots on the board. After nine turns, the board becomes an addition problem with three 3-digit numbers to add together. The goal is to …