Lesson: Multiply Decimals by Whole Numbers

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Lesson Objective

Multiply decimals (by decimals and by whole numbers)

Lesson Plan

 

Aim/Objective:

Key Points

Multiply decimals (by decimals and by whole numbers)

·         Multiplying with decimals is like multiplying with whole numbers. 

·         First, estimate.  Think about what product will be about. 

·         Next, multiply the digits.  You can use the traditional method or lattice method.

·         Then, place the decimal appropriately.  Use your estimation to help you

Assessment:

Jessica bought 4.75 pounds of bananas at $0.72 per pound.  How much did the bananas cost?

 

1.       Jeri practices running around the school track every day.  Her best time is 2.1 minutes.  It takes Denise one and a half times as long as Jeri.  How long does it take Denise to run around the track?

 

A.      0.6 min

B.      1.04 min

C.      3.15 min

D.      3.6 min

Lesson

Opening:

·         Students compute whole number problem:  24 x 63  1512

·         Using digits from answer students predict answers to:

0.24 x 6.3

A quarter of 6 is about 1 and some more so

1.512

24 x 0.63

a little more than half of 24 is a little more than 12 so

15.12

2.4 x 63

A little more than 2 times 63 is going to be a little more than 120 so

151.2

0.24 x 0.63

 

A little more than half of 0.24 is going to be 0.12 so

.1512

 

 

Intro to NM:

·         Walk through the steps of solving each problem

·         Model process of estimating prior to solving

·         Show the process using both the lattice and the traditional method

·         Model/Demonstrate how to place the decimal appropriately – using reasonableness (estimation) and rule

 

Guided Practice:

·         Students complete problems following steps and share answers

 

Independent Practice:

·         Students work on worksheet to practice multiplying with decimals

 

Lesson Resources

CW Multiply Decimals by Whole Numbers   Classwork
1,140
HW Unit 5 Multiply Decimals by Whole Numbers  
624

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