Everyday Math Lesson 12

1
Everyday Math Lesson 1-2

• Rectangular Arrays

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2
Key Concepts and Skills

• Find factors of a number
• Write number sentences for rectangular arrays
• Use the turn-around rule for multiplication

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3
Vocabulary Words Which words would you like to
talk about?

• Array and rectangular array
• Multiplication
• Commutative Property of Multiplication
• Matrix
• Columns Rows
• Counting Numbers
• Product
• Factors and Factor Pairs
• Number Models of Multiplication

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4
Mental Math Remember the Procedure?

• You need to write the numbers 1 through 8 on your
  whiteboard. This is where you will write the
  answers to the multiplication problems I read to
  you.
• During Mental Math, I will only read the problem
  once. You need to quickly write down your answer
  next to the problem number on your whiteboard.

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Mental Math

• Did you notice the different symbols we can use
  to show we are solving a multiplication problem?
• You can use x or

• 3 x 5
• 3 9
• 7 x 6
• 7 x 7
• 4 9
• 8 x 7
• 8 x 4
• 9 x 7

• 15
• 27
• 42
• 49
• 36
• 56
• 32
• 63

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Math Message

• Arrange the 12 counters you were given into as
  many different rectangular arrays as you can.
  Then choose and draw one of the arrays on your
  white board.
• Were going to share different arrays.
• How many ways can we come up with?
• 12 x 1 1 12 2 x 6 6 2, 3 by 4 4 3

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Array Museum What could you say that is true
about each of these pictures?
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Each array has these things in common

• Each row has the same number of objects
• Each column has the same number of objects
• Each array has a rectangular shape
• Lets look again and count the rows and columns
  in my Array Museum

Go back to the Array Museum
9
Array and Rectangular Array

• An array is
• An arrangement of objects in a regular pattern,
  usually in rows and columns.
• A rectangular array means that the objects in the
  array are lined up in rows and columns.
• How many rows?
• 5
• How many columns?
• 7

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A Rectangular Array has
The same number of items in each column
Columns 1 2
3 4
Row 1

• The same number of items in each row

Row 2
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Multiplication

• Multiplication is repeated adding of the same
  number.
• Example
• 3 5 33333 15
• Another example
• 5 x 4 is just adding
• 5555 5 x 4 20

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12
Commutative Property of Multiplication

• A rule that says changing the order of the
  numbers in a multiplication problem wont change
  the answer.
• Also called the turn- around facts.

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13
Matrix

• Matrix Method of doing multiplication problems
  uses boxes to break apart the numbers being
  multiplied.

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14
Columns Rows

• Columns go up and down
• Rows go left and right

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15
Counting Numbers

• It sounds so simple but counting numbers are just
  the numbers we use to show our problems
• 1, 2, 3, 4,5, 114, 230, 1,489 are all counting
  numbers.

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Factors and Factor Pairs

• Factors are one of two (or more) numbers that are
  multiplied together to give a product.
• For example
• 3 X 5 15

product
factors
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Products

• The product is the result of answering a
  multiplication problem.
• For example, the product of 5 x 30 is 150.

PRODUCT
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Number Models of Multiplication

• A number model of a multiplication problem is
  taking the array we see in a picture and turning
  it into numbers.
• For example The array is showing 2 rows times 3
  columns equals 6 pennies.
• The number model is
• 2 x 3 6

2 x 3 6
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Array Museum Count the Rows Columns
8 x 6 48
3 x 5 15
4 5 20
2 3 6
2 x 5 10
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Practice What Youve Learned

• Find page 5 in your SMJ the floppy book.
• Working with a partner, each of you needs to
  complete the questions on page 5 but you may work
  together.

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Addition and Subtraction Families
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HOMEWORK Due tomorrow

• Complete Study Link 1-2, More Array Play.
• Notice that the top half of the page has you
  drawing rectangular arrays and putting the number
  model underneath.
• The bottom part of the paper ask you to solve the
  problems WITHOUT using a calculator.