Collaborating Teachers

Collaborating Teachers Grades 4-5 October 9, 2013 Factors and Multiples & Distributive Property

Tile Activity • Count out 12 tiles. • Arrange them so that they form a rectangle.

Tile Activity • Count out 12 tiles. • Arrange them so that they form a rectangle. • What multiplication sentence could you write about your rectangle? • Where in your figure do you see the numbers in your multiplication sentence?

Tile Activity Suppose you made this rectangle.

Tile Activity What multiplication sentence could you write about your rectangle?

Tile Activity What multiplication sentence could you write about your rectangle? 3 x 4 = 12 (for example)

Tile Activity Where in your figure do you see the numbers in the math sentence? 3 x 4 = 12

Tile Activity 3 x 4 = 12 1 2 3 4 5 6 7 8 3 9 10 11 12 4

Tile Activity 1 2 3 4 We say that the numbers 3 and 4 are factors of 12. The number 12 is a multiple of 3 and a multiple of 4. 5 6 7 8 3 9 10 11 12 4

Tile Activity • Can you write a division sentence about your rectangle? • Where are the factors and multiples in your number sentence?

Tile Activity 12 ÷ 3 = 4, for example.

Tile Activity 12 ÷ 3 We say that the numbers 3 and 4 are factors of 12. The number 12 is a multiple of 3 and a multiple of 4. 1 2 3 4 5 6 7 8 3 9 10 11 12 4

Tile Activity • What other rectangle can you make with 12 tiles? • What factors and multiples does your new rectangle illustrate?

Tile Activity • Use your 12 tiles make a rectangle with a length of 7. • Does it work? • Is 7 a factor of 12? • Is 12 a multiple of 7? • What if you try to use your 12 tiles to make a rectangle with a length of 5? Do you think it will work? Why?

Tile Activity • What are ALL the rectangles you can make with 12 tiles? • What are ALL the factors of 12?

Tile Activity • On another day, do a similar activity with 20 tiles, 24, 30, 36, 48. Try the same activity with 13 tiles.

Factor and Multiple Games Online • HoodaMath – Factor Feeder www.hoodamath.com/games/factorfeeder.html 2) nrich Factors and Multiples Game www.nrich.maths.org/5468 3) BBC.UK – The Legend of Dick and Dom www.bbc.co.uk/bitesize/ks2/maths/number/factors_multiples/play

More Factor and Multiple Games Online 4) Johnnie’s Math Page – Ghost Multiples, Egg Multiples, and more www.jmathpage.com/JIMSMultiplicationfactorsandmultiples.html 5) Math Playground - Pumpkin Multiples and more www.mathplayground.com/multiples.html 6) Count On- Octopus factors www.counton.org/games/map-numbers/octopus

??? • How can you help your students build fluency with factors and multiples?

Distributive Property of Multiplication over Addition Let’s begin with some mental math. Solve these problems and remember what strategy you used: 8 x 24 3 x 56 9 x 53

Distributive Property of Multiplication over Addition Did your strategy incorporate the distributive property? 8 x 24 3 x 56 9 x 53

Distributive Property of Multiplicationover Addition Can you apply the distributive property to this problem? 32 x 15 Video 5.2 from Number Talks: Helping Children Build Mental Math and Computation Strategies by Sherry Parrish 5th grade teacher Lee Ann Davidson

Video 5.2 How did the students break the numbers apart? Is this the distributive property?

Introducing the Distributive Property Meaningfully • Using tiles, show how you would model: 4 x 3 – Choose one color of tile. 4 x 8 – Choose a different color of tile. 4 x (3 + 8) In your representation, how is the four distributed over the three and eight? How could you use these examples to build students’ understanding of the distributive property?

4 x 3 4 x 3

(4 x 3) + (4 + 8) (4 x 3) + (4 x 8)

3 + 8

4(3 + 8) 4(3 + 8)

Modeling with base 10 blocks Use base 10 blocks to model the following: 3 x 14 What mental math strategy could be represented by your base 10 blocks?

3 x 14 3 x 14 3 x 14 = (3 x 10) + (3 x 4) Now show 7 x 22 with base 10 blocks.

7 x 22 7 x 22 =

7 x 22 7 x 22 = ( 7 x 20 + (7 x 2) = 140 + 14 = 154

Or: 7 x 22 7 x 22 =

7 x 22 7 x 22 = (7 x 10) + (7x 12) = 70 + 84 = 154

Try 11 x 12

11 x 12

11 x 12 11 x 12 = (10 x 10) + (10 x 1) + (2 x 10) + ( 2 x 1) = 100 + 10 + 20 + 2 = 132

3 Methods for Multiplying 11 11 11 x 12x 12x 12 12 22 2 120 110 20 132 132 10 100 Which one would you use? 132 How do the other methods work?

11 x 12 11 X 12 22 110 132 110 + 22 = 132

11 x 12 11 X 12 12 120 132 120 + 12 = 132

11 x 12 11 X 12 2 20 10 100 132 100 + 10 + 20 + 2 = 132

??? • How can you help your students make sense of the distributive property of multiplication over addition?

Using the Distributive Property to Divide • 84 ÷ 6 • 6 x ? = 84

Using the Distributive Property to Divide • 84 ÷ 6 • 6 x ? = 84 • 60 + 24 = 84

Using the Distributive Property to Divide • 84 ÷ 6 • 6 x ? = 84 • 60 + 24 = 84 • 60 ÷ 6 = 10 • 24 ÷ 6 = 4

Using the Distributive Property to Divide • 84 ÷ 6 • 6 x ? = 84 • 60 + 24 = 84 • 60 ÷ 6 = 10 • 24 ÷ 6 = 4 • 84 ÷ 6 = 10 + 4 = 14

Collaborating Teachers