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Using the Area Model to Multiply Decimals

5.NBT.7

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Using the key, what equation can you write for the representation below?

Pose the Problem:

KEY

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Debrief:

2

3

We can see 2 rows. We see 3 ones represented in each row, for a total value of 6 ones.

We can write the equation:

2 x 3 = 6

KEY

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Using the key, what equation can you write for the representation below?

Pose the Problem:

KEY

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Debrief:

We can see 2 rows.

​

1.4 is represented in each row.

​

2

1.4

KEY

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Debrief:

2

1.4

1 + 0.4

This representation helps us make sense of the partial products strategy. We can decompose

1.4 to 1 and 0.4

​

2 x 1 = 2

2 x 0.4 = 0.8

​

2 + 0.8 = 2.8, so we can write the equation 2 x 1.4 = 2.8

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Using the key, what expression can you write for the representation below?

Pose the Problem:

KEY

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Debrief:

This representation shows 1.5 x 2.3.

​

We can see 1.5 rows.

​

2.3 is represented in 1 row.

1.5

2.3

KEY

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Debrief:

We can see 1.5 rows.

2.3 is represented in 1 row.

​

0.5 of 2.3 is represented here.

0.5

2.3

1

KEY

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Now solve 1.5 x 2.3

Pose the Problem:

KEY

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Debrief:

2.3

2 + 0.3

We can decompose 2.3 to 2 and 0.3.

​

We can decompose 1.5 to 1 and 0.5.

​

1.5

​

1

+

0.5

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Debrief:

2

2.3

2 + 0.3

​

2 x 1 = 2

​

2 x 0.5 = 1

​

1.5

​

1

+

0.5

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Debrief:

2.3

2 + 0.3

​

1 x 0.3 = 0.3

​

0.5 x 0.3 = 0.15

​

​

1.5

​

1

+

0.5

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Debrief:

2

2.3

2 + 0.3

1.5

​

1

+

0.5

​

2 + 1 + 0.3 + 0.15 =3.45

​

1.5 x 2.3 = 3.45

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Now itโ€™s Your Turn:

Use the Tiles tab to click on Numbers. Then click on Multiplication Grid

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Click on the X to close this selection screen and give you more space to work.

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You can also click on the zoom in and zoom out buttons to adjust your workspace

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Now itโ€™s Your Turn:

This helps you

shrink or expand the columns.

This helps you

shrink or expand the rows.

This helps you rotate your model

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Practice Notes

  • The following slides are intended to provide more opportunity for students to model and solve multiplication with decimals problems using an area model.
  • Consider changing the slide deck from โ€˜Instructor-pacedโ€™ to โ€˜student-paced.โ€™
  • Directions to change Pear-Deck mode from โ€˜Instructor-Pacedโ€ to โ€œStudent- Pacedโ€ once the lesson has started:
    • Click on the โ€˜peapodโ€™ from the teacher dashboard.
    • Click on โ€˜Turn on Student-Pacedโ€™

​

​

​

​

​

​

1

2

  • Please delete these notes slides or move them to the beginning or end of the slide deck. They are set to skip, but this function does not work in Pear Deck.

​

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Use the Multiplication Grid to

represent 2.1 x .4.

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Is this the Multiplication Grid you created to

represent 2.1 x .4?

Notice that there are 2.1 rows, with 0.4 represented in each row.

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What is the product of 2.1 x .4?

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Use the Multiplication Grid to

represent 1.3 x 1.6.

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Is this the Multiplication Grid you created to

represent 1.3 x 1.6?

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What is the product of 1.3 x 1.6?

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Practice:

Draw an area model and solve for:

2 x 1.7

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Practice:

Draw an area model and solve for:

3.2 x 1.5

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Practice:

Draw an area model and solve for:

0.3 x 0.6

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Using the Area Model to Multiply Decimals

5.NBT.7