# Using Know Facts to Find Unknown Facts by zhangyun

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```									Using Know Facts to
Find Unknown Facts
Math
3.3
Objective

 Use the distributive property to
find products by breaking
unknown facts into known facts
Vocabulary

 Distributive Property – breaking apart
problems into two simpler problems

 Example: (3 x 21) = (3 x 20) + (3 x 1)
Investigating the Concept
Two-Tone Rectangles
 Need Centimeter Grid Paper (T.T. 6);markers
 Outline two 4-by-6 rectangular arrays on the
grid paper.
 Shade the first grid in one color.
 What multiplication fact does this array show?
 Color the second array so that it makes two
arrays: one 4-by-5 and the other 4-by-1
 What multiplication facts do these arrays
show?
Arranging the Facts
 Need Red and Blue Construction paper
 Hang a 5-by-6 array of red sheets of
construction paper on the board.
 What multiplication fact does this array show?
 I need a volunteer to cover the last column with
pieces of blue construction paper.
 What multiplication fact do the red sheets now
show?
 What is the sum of the red and blue sheets of
paper.
How can I break apart
facts?
 The distributive property
shows that you can break
apart facts to find the
product.
Distributive Property
 3x5=2x5+1x5

 5 stays the same but the 3 is broken apart to 2
and 1.
 Example
 (3 x 6) = (2 x 6) + (1 x 6)
 Why would you want to break apart 3 x 6
 2 x 6 = 12
 1x6=6
 12 + 6 = 18
 So 3 x 6 must equal 18

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