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Module 1 Lessons 7 & 8 Demonstrate the COMMUTIVITY of multiplication, and practice related facts by skip-counting objects in array models.

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Module 1 Lesson 12

Module 1Lessons 7 & 8Demonstrate the COMMUTIVITY of multiplication, and practice related factsby skip-counting objects in array models.

Skip Count By 2s To 20 2468101214161820Skip Count by 3s to 30 36912151821242730Skip Count by 4s to 40 481216202428323640

Skip CountDivide Equal GroupsWrite an addition sentence for these arrays.4 + 4 = 8Write a division sentence for 8 divided into two equal groups.8 2 = 4Write a division sentence for 8 divided into four equal groups.8 4 = 2Divide Equal GroupsWrite an addition sentence for these arrays.4 + 4 + 4 = 12Write a division sentence for 12 divided into three equal groups.12 3 = 4Write a division sentence for 12 divided into four equal groups.12 4 = 3Multiply with twos

As I uncover groups of two, say the multiplication sentence.c1 x 2 = 22 x 2 = 4c3 x 2 = 6c4 x 2 = 8c5 x 2 = 10c6 x 2 = 12c7 x 2 = 14c8 x 2 = 16c9x 2 = 18c10x 2 = 20Application ProblemAnna picks 24 flowers. She makes equal bundles of flowers and gives 1 bundle each to her 7 friends. She keeps a bundle for herself, too. How many flowers does Anna put in each bundle?

Rotate Arrays 90 degrees

Draw the array at the left on your white board.

Then skip count by 2s to find the total.2468Write a multiplication sentence where the first factor is the number of rows.4 x 2 = 8Rotate Arrays 90 degrees

Now, take your board and turn it 90 degrees.48Lets skip count the rows again, and write a new multiplication sentence where the first factor is the number of rows.2 x 4 = 8

Commutative Property

Talk to your partner: What do you notice about the factors in these multiplication sentences?The factors are the same, but they switched places!Commutative PropertyThe COMMUTATIVE PROPERTY is the Law of Math that says you can swap numbers around and still get the same answer when you add or multiply.

I like to call this the MOVE IT MOVE IT property!

Lets practice!

Interpreting Rows & ColumnsOn your board, draw an array that shows 5 rows & 3 columns.

Write and equation to match your array. Dont solve it yet!5 x 3 = _____Interpreting Rows & ColumnsNow, WITHOUT erasing, change your array to show 3 x 5.

Write a new equation to match your array. Dont solve it yet!3 x 5 = _____Interpreting Rows & ColumnsExplain the difference between these two problems to your partner.

We used commutative property to switch the factors.Did the total change?NO!3 x 55 x 3Interpreting Rows & ColumnsLets skip count to solve the problems.

5 x 3 = 153 x 5 = 155 x 3 = 3 x 5 = 153 x 55 x 3369121551015Commutative Multiplying 4 x 2 = 2 x ______4

Commutative Multiplying

3 x 2 = 2 x ______3Commutative Multiplying 5 x 9 = 9 x ______5

Check Yourself!Children in Mrs. Richardsons class sit in 2 rows of 9 on the carpet for story time. Erin says, We make 2 equal groups. Vincent says, We make 9 equal groups. Who is correct? Explain how you know using models, numbers, and words.

Erin and Vincent are both correct BECAUSE the answer depends on how you look at the array.If Erins array is turned sideways, it looks like Vincents. Theyre the same!Problem Sets