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10.08 Distributive property using area

Lesson

Are you ready?

Can you find the area of a rectangle?

Find the area of the rectangle shown.

width = $3$3 cm
length = $9$9 cm  
  1. $\text{Area }$Area $=$= $\text{length }\times\text{width }$length ×width cm2  
    $\text{Area }$Area $=$= $\editable{}\times\editable{}$× cm2 (Fill in the values for the length and width.)
    $\text{Area }$Area $=$= $\editable{}$ cm2 (Complete the multiplication to find the area.)

Learn

This video introduces the distributive property.

Apply

question 1

We want to use the distributive property to rewrite $2\times19$2×19 as easier multiplications.

  1. This diagram shows how $2$2 groups of $19$19 objects can be split up.



    Use the diagram to fill in the blank to make the statement true.

    $2\times19=2\times\left(10+\editable{}\right)$2×19=2×(10+)

  2. Fill in the blanks to show how $2$2 groups of $\left(10+9\right)$(10+9) can be split up into smaller multiplications.

    $2\times\left(10+9\right)=2\times10+2\times\editable{}$2×(10+9)=2×10+2×

Learn

This video shows us how to use the distributive property to solve problems. 

Apply

question 2

We want to find $2\times42$2×42.

  1. Use the area model to complete the following:

              $40$40           $2$2  
    $2$2                        
                       
    $2\times42$2×42 $=$= $2\times\left(40+2\right)$2×(40+2)
      $=$= $2\times\editable{}+2\times2$2×+2×2
      $=$= $\editable{}+\editable{}$+
      $=$= $\editable{}$

 

Remember!

We can represent the distributive property as splitting a rectangle into two parts, finding the area of each part and then adding them together.

Outcomes

3.OA.B.5

Apply properties of operations as strategies to multiply and divide. (Students need not use formal terms for these properties.) Examples: If 6 x 4 = 24 is known, then 4 x 6 = 24 is also known (commutative property of multiplication). 3 x 5 x 2 can be solved by (3 x 5) x 2 or 3 x (5 x 2) (associative property of multiplication). One way to find 8 x 7 is by using 8 x (5 + 2) = (8 x 5) + (8 x 2). By knowing that 8 x 5 = 40 and 8 x 2 = 16, then 8 x 7 = 40 + 16 = 56 (distributive property of multiplication over addition).

3.MD.C.7

Relate area of rectangles to the operations of multiplication and addition.

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