www.everydaymathonline.com

Lesson 2�7 135

Advance PreparationPlan to spend two days on this lesson.

Teacher’s Reference Manual, Grades 1–3 pp. 97–99, 102–105, 186–190, 200, 201

Key Concepts and Skills• Model multidigit numbers with base-10

blocks. [Number and Numeration Goal 1]

• Use basic facts to solve extended fact

problems with the partial-sums algorithm. 

[Operations and Computation Goal 1]

• Use base-10 blocks to extend the

partial-sums algorithm to 3-digit addends. 

[Operations and Computation Goal 2]

• Make ballpark estimates as a check for

reasonableness of answers. 

[Operations and Computation Goal 5]

Key ActivitiesChildren add 2- and 3-digit numbers, discuss

solution methods, and make ballpark

estimates to check addition results.

Ongoing Assessment: Recognizing Student Achievement Use journal page 45. [Operations and Computation Goal 2]

Key Vocabularypartial-sums algorithm � ballpark estimate �

rounding � partial-sums method

MaterialsMath Journal 1, p. 45

Student Reference Book, pp. 190–194

Home Link 2�6

Math Masters, p. 53 (optional)

base-10 blocks � overhead base-10 blocks

(optional)

Playing Target: 50Student Reference Book, pp. 312

and 313

Math Masters, pp. 411 and 465

per partnership: 4 each of number

cards 0–9 (from the Everything Math

Deck, if available), base-10 blocks

Children practice multidigit addition

and subtraction.

Math Boxes 2�7Math Journal 1, p. 46

Children practice and maintain skills

through Math Box problems.

Home Link 2�7Math Masters, p. 52

Children practice and maintain skills

through Home Link activities.

READINESS

Modeling 2-Digit Numbers with Base-10 BlocksMath Masters, p. 411

4 each of number cards 0–9 (from the

Everything Math Deck, if available) �

base-10 blocks � half-sheet of paper

Children use base-10 blocks to model 2-digit

numbers.

ENRICHMENTMaking Up Addition Problems from a Mileage MapStudent Reference Book, pp. 224 and 225

Math Masters, p. 407

Children make up and solve 3-digit addition

number stories based on a mileage map.

ELL SUPPORTBuilding a Math Word BankDifferentiation Handbook, p. 132

Children write the term ballpark estimate

using the Word Bank template.

Teaching the Lesson Ongoing Learning & Practice

132

4

Differentiation Options

The Partial-Sums Algorithm

Objectives To guide children as they make ballpark estimates;

and to provide opportunities to model and practice the partial-

sums algorithm for 2- and 3-digit numbers.

a

��������

eToolkitePresentations Interactive Teacher’s

Lesson Guide

Algorithms Practice

EM FactsWorkshop Game™

AssessmentManagement

Family Letters

CurriculumFocal Points

Common Core State Standards

135_EMCS_T_TLG1_G3_U02_L07_576809.indd 135135_EMCS_T_TLG1_G3_U02_L07_576809.indd 135 2/4/11 9:36 AM2/4/11 9:36 AM

136 Unit 2 Adding and Subtracting Whole Numbers

1 Teaching the Lesson

� Math Message WHOLE-CLASSDISCUSSION

Follow-UpAsk children how they calculated the answers. Record children’s different strategies on the board. During the discussion, have children name the value in each place, not just the digits. In the first problem, for example, if a child says, “I added the 6 and the 2” remind the class to say they added 60 and 20, or 6 tens and 2 tens.

Possible Strategies for 28 + 37

� 20 + 30 = 50; 8 + 7 = 15; and 50 + 15 = 65. This strategy uses the partial-sums algorithm.

� Take 2 from 37, getting 35, and add the 2 to 28; 28 + 2 = 30, and 30 + 35 = 65.

� Think of 37 as 30 + 7; 28 + 7 = 35; and 35 + 30 = 65.

� Making Ballpark WHOLE-CLASS ACTIVITY

Estimates(Student Reference Book, pp. 190–193)

Remind children that answers should always be checked to see whether they make sense. This is true for number story problems and for problems where there is no story like those in the Math Message.

Children should make a ballpark estimate of an answer either before or after calculating to help solve a problem or check an answer. One way to make an estimate is by changing the numbers in a problem to close-but-easier numbers and then adding or subtracting them. Have children read about estimation on pages 190–193 in the Student Reference Book.

PROBLEMBBBBBBBBBBBOOOOOOOOOOOBBBBBBBBBBBBBBBBBBBBBBBBBB MMMMMEEEEMMMMLEBLELBLEBLELLLBLEBLEBLEBLEBLEBLEBLEBLEEEMMMMMMMMMMMMMMOOOOOOOOOOOOBBBBBBBBLBLBLBLBLBLLLLLLLPROPROPROPROPROPROPROPROPROPROPROPPRPROPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPRORROROROOROOPPPPPPP MMMMMMMMMMMMMMMMMMMEEEEEEEEEEEELELELEEEEEEEEEELLLLLLLLLLLLLLLLLLLLLLRRRRRRRRRRRRRRRRPROBLEMSOLVING

BBBBBBBBBBBBBBBBBBBBLELEELEMMMMMMMOOOOOOOOBBLBLBBLBLBBBBLLOOROROROORORORORORORORO LELELELEEEEEELEMMMMMMMMMMMMLEMLLLLLLLLLLLLLLLLLLLLLRRRRRRRRRRGGGGGLLLLLLLLLLLLLVINVINVINVINNNNVINVINVINVINNVINVINVINVINV GGGGGGGGGGGGOLOOOOLOOLOLOLOO VVINVINLLLLLLLLLLVINVINVINVINVINVINVINVINVINVINVINVINVINVINNGGGGGGGGGGGOOOLOLOLOLOLLOOO VVVLLLLLLLLLLVVVVVVVVVVSOSOSOOSOSOSOSOSOSOOSOSOSOSOSOOOSOOSOSOSOSOSOSOSOOSOSOSOSOSOSOSOSOSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS VVVVVVVVVVVVVVVVVVVVVLLLLLLLVVVVVVVVVLLVVVVVVVVLLLLLLLLVVVVVLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLSSSSSSSSSSSSSSSSSSSSSS GGGGGGGGGGGGGGGGOOOOOOOOOOOOOOOOOOO GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGNNNNNNNNNNNNNNNNNNNNNNNNNIIIIIIIIIIIIIIIIIIIISOLVING

Getting Started

Math MessageAdd.

63 + 24 = 87

28 + 37 = 65

49 + 18 = 67

Home Link 2�6 Follow-Up Review answers as necessary. Have a few children share their strategies for solving the number stories.

Mental Math and Reflexes Ask such questions as the following:

Is 42 closer to 40 or 50? 40

Is 56 closer to 50 or 60? 60

Is 95 closer to 90 or 100? Same distance away

Is 150 closer to 100 or 200? Same distance away

Is 210 closer to 200 or 300? 200

Is 998 closer to 900 or 1,000? 1,000

Is 2,068 closer to 2,000 or 2,100? 2,100

Is 3,243 closer to 3,240 or 3,250? 3,240

Is 4,250 closer to 4,200 or 4,300? Same distance away

Unit

miles

NOTE Partial sums may be calculated in

either order—it does not matter whether

you add the tens or the ones first. When

discussing and using the partial-sums

algorithm, emphasize the following

paper-and-pencil method. Example: 63 + 24

1. Add the tens:

6 [tens] + 2 [tens] = 8 [tens] or 80.

Write 80 below the line.

2. Add the ones:

3 [ones] + 4 [ones] = 7 [ones] or 7.

Write 7 below the 80.

3. Add the partial sums: Draw a second

line beneath 80 and 7. Write 87 beneath

this line.

NOTE Plan to spend two days on this

lesson.

1. Add the 10s.

2. Add the 1s.

3. Add the partial sums.

10s 6

+ 2

8 8

1s

3

4

0 77

EM3cuG3TLG1_136-140_U02L07.indd 136EM3cuG3TLG1_136-140_U02L07.indd 136 12/30/10 11:57 AM12/30/10 11:57 AM

Ask children to make ballpark estimates for the problems below and tell how they arrived at their estimates. Note that there is often more than one acceptable estimate.

� 42 + 89 is close to 40 + 90 = 130

� 23 + 71 is close to 20 + 70 = 90

� 148 + 51 is close to 150 + 50 = 200

� 213 + 468 is close to 200 + 500 = 700 or 210 + 470 = 680

� 35 + 63 is close to 30 + 60 = 90 or 40 + 60 = 100. Point out that because 35 is halfway between 30 and 40 on the number line, either 30 or 40 may be used as an easier substitute for 35.

� Rounding to the WHOLE-CLASS ACTIVITY

Nearest 10 or 100(Student Reference Book, p. 194)

Rounding can also help you estimate. We round numbers to make them easier to work with or understand. Numbers are often rounded to the nearest 10, 100, 1,000, and so on. For example, 769 rounded to the nearest 100 is 800.

The following describes three methods for rounding numbers.

Three Methods for Rounding

Method 1

Write the following table on the board.

Ask: How many floors does the Bank of America Tower in New York have? 54 As a class, work through the number-line method to round 54 to the nearest ten.

1. Draw the following number line on the board.

Lesson 2�7 137

Four Tallest Buildings in the United States in 2011

Building Height Number of Floors

Willis Tower (formerly Sears Tower), 1,451 ft 110

Chicago

Trump International Hotel & Tower, 1,389 ft 92

Chicago

Empire State Building, New York 1,250 ft 102

Bank of America Tower, New York 1,200 ft 54

136-140_EMCS_T_TLG1_G3_U02_L07_576809.indd 137136-140_EMCS_T_TLG1_G3_U02_L07_576809.indd 137 1/24/11 4:27 PM1/24/11 4:27 PM

2. Ask which two multiples of 10 are closest to 54. Have children skip count by 10s to help them decide. 10, 20, 30, 40, 50, 60, 70, … Help them conclude that since 54 is between the multiples of 50 and 60, they are the closest multiples. Record 50 and 60 on the number line.

50 60

Ask a volunteer to write the number that is halfway between the lower and higher numbers on the number line. 55

50 55 60

3. Invite another volunteer to mark the approximate location of 54 on the number line.

50 5554 60

4. Ask: Is 54 closer to the lower number or to the higher number? Lower number What is 54 rounded to the nearest ten? 50

Draw another number line and say: Use the number-line method to round the number of floors in the Trump International Hotel & Tower to the nearest 10. 90 floors

90 9592 100

Method 2

As a class, read and discuss another method for rounding on Student Reference Book, page 194. Using this method, what would be the height of the Trump International Hotel & Tower rounded to the nearest hundred feet? 1,400 feet

1. Write the number you are rounding. Underline 1 3 8 9the digit in the place to which you are rounding.

2. Replace all digits to the right of the underlined 1 3 0 0digit with 0. This is the lower number.

3. Add 1 to the underlined digit and leave the 1 4 0 0digits to the right as 0. This is the higher number.

4. Ask yourself: Is the number I am rounding closer to the lower number or the higher number?

5. Round to the closer of the two numbers. 1 4 0 0

Method 3

The third rounding method uses reasoning to compress the steps of the previous methods. Consider rounding 54 to the nearest 10.

1. Write the number and underline the digit in 5 4the place to which you are rounding.

2. Look at the digit to the right of the place to 5 4which you are rounding.

3. If that digit is less than 5, round down. If that 5 0 digit is equal to or greater than 5, round up.

137A Unit 2 Adding and Subtracting Whole Numbers

Round each number.1. 78 2. 34 3. 85 4. 555 5. 4,3026. Estimate the sum of 282 � 47 by using rounded numbers.

Check your answers on page 342.

194 one hundred ninety-four

A more accurate way to adjust numbers is to round the numbers. Here is a way to round a number.

Estimation

Step 1 Write the number you are rounding.

Step 2 Keep the first digit. Replace the other digits by zeros. This is the lower number.

Step 3 Add 1 to the first digit. This is the higher number.

Step 4 Is the number you are rounding closer tothe lower number or the higher number?

Step 5 Round to the closer of the two numbers.

Round 68 Round 52968 529

60 500

70 600

higher lower

70 500

You are rounding 45.The lower number is 40. The higher number is 50. 45 is halfway between 40 and 50.

So round 45 to 50, which is the higher number.

Sometimes the number you are rounding is halfwaybetween the lower number and the higher number. When this happens, round to the higher number.

Student Resource Book, p. 194

Student Page

EM3cuG3TLG1_136-140_U02L07.indd A136EM3cuG3TLG1_136-140_U02L07.indd A136 12/30/10 11:57 AM12/30/10 11:57 AM

Explain to children that when they round down, the digit in the place they are rounding to stays the same. When they round up, the digit they are rounding to increases by 1. Ask children to use Method 3 to find the height of the Willis Tower rounded to the nearest hundred. 1,500 feet

Have partnerships choose any method and work through the Check Your Understanding problems at the bottom of Student Reference Book, page 194. Bring the class together to share solution strategies.

� Modeling the WHOLE-CLASS ACTIVITY

Partial-Sums Methodfor 3-Digit Addends(Math Masters, p. 53)

Remind children that in Second Grade Everyday Mathematics they used the partial-sums method to add 2- and 3-digit addends. Today you will review how the partial-sums method works with 3-digit addends.

Write these problems on the board 145 169 + 322 + 175in vertical form:

Ask children to gather in a circle as you demonstrate with base-10 blocks, or use base-10 blocks on the overhead projector. Refer to flats as hundreds, longs as tens, and cubes as ones. For each problem, model addition as a four-part operation: add the 100s, add the 10s, add the 1s, and then add the partial sums.

Example 1: Model 145 + 322 with base-10 blocks.

� Count out 1 flat, 4 longs, and 5 cubes to represent 145. Count out 3 flats, 2 longs, and 2 cubes to represent 322.

� Arrange the blocks like the addition problem in vertical form.

� Gather the hundreds into one pile, the tens into a second pile, and the ones into a third pile.

� Count the hundreds. 4 hundreds, or 400 Count the tens. 6 tens, or 60 Count the ones. 7 ones, or 7

� Add the hundreds, tens, and ones. 400 + 60 + 7 = 467

� Ask children how they would record this procedure on paper. You may use Math Masters, page 53 if you wish.

PROBLEMBBBBBBBBBBOOOOOOOOOOOBBBBBBBBBBBBBBBBBBBBBBBBBBBB MMMMEEEMBLBLELBLEBLELLLBLEBLEBLEBLEBLEBLEBLEBLEEEMMMMMMMMMMMMMMOOOOOOOOOOOOBBBBBBLBLBBLBLBLLBLLLLPROPROPROPROPROPROPROPROPROPROPROPROPPRPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPROROOROROROROROOPPPPPPP MMMMMMMMMMMMMMMMMMMMEEEEEEEEEEEEELELELEEEEEEEEELLLLLLLLLLLLLLLLLLLLLLRRRRRRRRRRRRRRRRPROBLEMSOLVING

BBBBBBBBBBBBBBBBBBBB EEELEMMMMMMMMOOOOOOOOOOBBBBLBLBLBLBBLBBROROOROROROROROROROROROROO LELELELEEEEEELEMMMMMMMMMMMMLEMLLLLLLLLLLLLLLLLLLLLLRRRRRRRRRRRGGGLLLLLLLLLLLLLVINVINVINVINVINVINNNVINVINVINNVINVINVINVINV GGGGGGGGGGGOLOOOLOOLOOLOO VINVINVLLLLLLLLLLVINVINVINVINVINVINVINVINVINVINVINVINVINV NGGGGGGGGGGOLOLOLOLOLOLOLOOOLO VVVVVLLLLLLLLLLVVVVVVVVVOSOSOOSOSOSOSOSOSOSOOSOSOOOOOOSOSOSOSOSOSOSOSOSOOOSOOSOSOSOSOSOSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS VVVVVVVVVVVVVVVVVVVVVLLLVVVVVVVVLLVVVVVVVVLLLLLLLLVVVVVLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLSSSSSSSSSSSSSSSSSSSSS GGGGGGGGGGGGGGGGGGOOOOOOOOOOOOOOOOOOOO GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGNNNNNNNNNNNNNNNNNNNNNNNNNNIIIIIIIIIIIIIIIIIIISOLVING

Lesson 2�7 137B

1. Add the 100s.

2. Add the 10s.

3. Add the 1s.

4. Add the partial sums.

100s

1

+ 3

4 4

10s

4

2

0 6

6

1s

5

2

0077

400 + 60 + 7 = 467

+

53

LESSON

2�7

Name Date Time

Addition: The Partial-Sums Method

100s3

� 4

7

�7

10s21

031 4

1s98

0077

Example: Ballpark estimate:

1. Ballpark estimate:

3. Ballpark estimate:

2. Ballpark estimate:

4. Ballpark estimate:

300 � 400 � 700

100s 10s 1s 100s 10s 1s

100s 10s 1s 100s 10s 1s

Math Master, p. 53

Teaching Master

Algorithm Project The focus of this

lesson is the partial-sums method. To teach

U.S. traditional addition, see Algorithm

Project 1 on page A1.

EM3cuG3TLG1_136-140_U02L07.indd A137EM3cuG3TLG1_136-140_U02L07.indd A137 12/30/10 11:57 AM12/30/10 11:57 AM

138 Unit 2 Adding and Subtracting Whole Numbers

200 + 130 + 14 = 344

+

Date Time

Make a ballpark estimate. Write a number model to show your estimate.Choose at least two problems to solve using the partial-sums methodand show your work. You may choose any method you wish to solve the other problems.

Unitmiles

Example:

Ballpark estimate:

Partial-Sums Method

3. Ballpark estimate:

1. Ballpark estimate:

4. Ballpark estimate:

2. Ballpark estimate:

5. Ballpark estimate:

300�400 � 700 9 0� 3 7

127

Addition MethodsLESSON

2�7

4 3� 2 6

69

� �Sample estimates given.

40 � 30 � 70

380 � 400 � 780 170 � 110 � 280 90 � 110 � 200

90 � 40 � 130

+

100s3

� 4

7

7

10s21

031 4

1s98

0077

1 7 2� 1 0 9

2813 7 8

� 4 0 1

7798 7

� 1 1 3

200

Math Journal 1, p. 45

Student Page

Adjusting the Activity Write each addend in expanded notation before adding. For example,

in 145 + 322 rewrite each number in expanded notation.

145 = 100 + 40 + 5

322 = 300 + 20 + 2

Write out each partial sum based on the expanded notation.

100 + 300 = 400

40 + 20 = 60

5 + 2 = 7

A U D I T O R Y � K I N E S T H E T I C � T A C T I L E � V I S U A L

Example 2: Model 169 + 175 with base-10 blocks.

� Count out and arrange the blocks as before. Gather the hundreds, tens, and ones into separate piles.

� Children might notice that the 13 tens can be replaced by 1 hundred and 3 tens. The 14 ones can be replaced by 1 ten and 4 ones. Make these substitutions, but leave the 1 hundred and 3 tens in the tens pile, and leave the 1 ten and 4 ones in the ones pile.

� Add the hundreds, tens, and ones: 200 + 130 + 14 = 344. Show children how to record this procedure on paper.

Try more 3-digit addition problems as needed.

� Practicing the Partial-Sums INDEPENDENTACTIVITY

Algorithm and Other Addition Methods(Math Journal 1, p. 45; Math Masters, p. 53)

Children should show their work on the journal page. Remind them to make ballpark estimates for checking their answers and for finding mistakes if an answer seems unreasonable. Provide base-10 blocks for children to use. Children may share their answers with a partner. If there is a disagreement, encourage them to discuss their strategies with each other and do the problem again until they both can agree on an answer. Abundant practice will be found on Home Link and Math Boxes pages in future lessons. Additional problems may be created on Math Masters, page 53.

Ongoing Assessment:Recognizing Student Achievement

Journal Page 45Problems1 and 2 �

Use journal page 45, Problems 1 and 2, to assess children’s ability to solve

multidigit addition problems. Children are making adequate progress if they are

able to solve Problems 1 and 2 correctly, with or without the use of manipulatives.

Some children may be able to solve the rest of the problems on the page, with or

without manipulatives.

[Operations and Computation Goal 2]

PROBLEMBBBBBBBBBBOOOOOOOOOOOBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB MMMMMEEBLEBLBLELBLLLLBLEBLEBLEBLEBLEBLEBLEBLEEEMMMMMMMMMMMMMMOOOOOOOOOOOBBBBBLBLBLBBLLLBLLLLPROPROPROPROPROPROPROPROPROPROPPRPROPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPROROOROROROROROOPPPPPPP MMMMMMMMMMMMMMMMMMMMMMMMEEEEEEEEEEEEEEEEELELELEEEEEEEEEELLLLLLLLLLLLLLLLLLLLLLLRRRRRRRRRRRRRRRRRRPROBLEMSOLVING

BBBBBBBBBBBBBBBBBBBB EELEMMMMMMMMOOOOOOOOOBBBLBLBLBBLBBROROOROROROROROROROROROROO LELELELEEEEEELEEMMMMMMMMMMMMLEMLLLLLLLLLLLLLLLLLLLLLRRRRRRRRRRGGGLLLLLLLLLLLLLVINVINVINV NNVINVINVINNVINVINVINVINVINV GGGGGGGGGGGOLOOOOLOOLOOLOO VINVINVINVLLLLLLLLLVINVINVINVINVINVINVINVINVINVINVINVINNGGGGGGGGGGGOLOLOLOLOLOLOLOOOLVVVVLLLLLLLLLLVVVVVVVVOSSOOSOSOSOSOSOSOSOSOSOSOSOOOOOSOSOSOSOSOSOSOSOSOSOSOSOOSOSOSOSOSOSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS VVVVVVVVVVVVVVVVVVVVVVLLLLLVVVVVVVVVLLLVVVVVVVVLLLLLLLLVVVVVLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLSSSSSSSSSSSSSSSSSSSSSSS GGGGGGGGGGGGGGGGGOOOOOOOOOOOOOOOOOOOO GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGNNNNNNNNNNNNNNNNNNNNNNNNNNNIIIIIIIIIIIIIIIIIIISOLVING

1. Add the 100s.

2. Add the 10s.

3. Add the 1s.

4. Add the partial sums.

100s

1

+ 1

2 1 3

10s

6

7

0 314

1s

9

5

0044

EM3cuG3TLG1_136-140_U02L07.indd 138EM3cuG3TLG1_136-140_U02L07.indd 138 12/30/10 11:57 AM12/30/10 11:57 AM

2 Ongoing Learning & Practice

� Playing Target: 50 PARTNER ACTIVITY

(Student Reference Book, p. 312; Math Masters,

pp. 411 and 465)

Children practice multidigit addition and subtraction with base-10 blocks by playing Target: 50. Go over the rules for Target: 50 on page 312 in the Student Reference Book.

NOTE The Target: 50 Record Sheet on Math Masters, page 465 may be used as

an assessment tool. Have children record one series of turns taken to reach 50.

� Math Boxes 2�7 INDEPENDENTACTIVITY

(Math Journal 1, p. 46)

Mixed Practice Math Boxes in this lesson are linked with Math Boxes in Lessons 2-5 and 2-9. The skill in Problem 6 previews Unit 3 content.

Writing/Reasoning Have children write an answer to the following: Explain how you found the length of the fence in Problem 6. Sample answer: I added all of the sides.

� Home Link 2�7 INDEPENDENTACTIVITY

(Math Masters, p. 52)

Home Connection Children solve addition problems using 2- and 3-digit numbers. Since the partial-sums algorithm might not be familiar to parents, you might want to send home the Student Reference Book.

PROBLEMBBBBBBBBBBBOOOOOOOOOOOBBBBBBBBBBBBBBBBBBBBBBBBB MMMMMEEEMMMBLEBLLELBLLLLBLEBLEBLEBLEBLEBLEBLEEEEMMMMMMMMMMMMMMOOOOOOOOOOBBBBBBLBLBLBBLBLLLLLPROPROPROPROPROPROPROPROPROPRORPPRPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPROROROROROROROOPPPPPPP MMMMMMMMMMMMMMMMMMMEEEEEEEEEEEELLELEEEEEEEEEELLLLLLLLLLLLLLLLLLLLRRRRRRRRRRRRRRRRRPROBLEMSOLVING

BBBBBBBBBBBBBBBBBBBB ELEELEEMMMMMMMMMMOOOOOOOOOBBBLBBLBLBBLBBLOOORORORORORORORORORORORO LELELELEEEEEELEMMMMMMMMMMMMLEMLLLLLLLLLLLLLLLLLLLRRRRRRRRRRGGGGGLLLLLLLLLLLLLVINVINVINVINVINVINNNNVINVINNVINVINVINVINV GGGGGGGGGGGGOLOOOLOOOOLOOO VVINVINLLLLLLLLLLVINVINVINVINVINVINVINVINVINVINVINVINVINVINVINGGGGGGGGGGGOOOLOLOLOLOLLOOO VVVVVVLLLLLLLLLLLLVVVVVVVVVVOSOSOSOOSOSOSOSOSOSOOSOSOSOSOOOSOOOSOSOSOSOSOSOSOOSOSOSOSOSOSOSOSOSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS VVVVVVVVVVVVVVVVVVVVVLLLLLLLVVVVVVVVVLLVVVVVVVLLLLLLLLVVVVVVLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLSSSSSSSSSSSSSSSSSSSSSSSSS GGGGGGGGGGGGGGGGGOOOOOOOOOOOOOOOOO GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGNNNNNNNNNNNNNNNNNNNNNNNNNIIIIIIIIIIIIIIIIIIIIISOLVING

Lesson 2�7 139

5. Austin read his book for 45 minutes

on Monday and for 25 minutes on

Tuesday. How many more minutes

did he read on Monday?

minutes

3. In 1,532,

the 1 means

the 5 means

the 3 means

the 2 means

Date Time

46

2. “What’s My Rule?”

4. Write at least 5 names for 1,000.

6. How long is the fence around the

flowers?

feet

1. Use addition or subtraction to

complete these problems on your

calculator.

Enter Change to How?

173 873

4,501 1,501

5,604 6,604

9,646 9,346

in out

4 12

0 21

Math BoxesLESSON

2�7

Quantity

Quantity

Difference

18, 19, 264

203 204

258

18 19

150 151

1,000

14 15

in

out

Add 9

Rule

3 feet

3 feet

2 feet2 feet

Answers vary.

10 × 100 1,000 × 1

2,000 − 1,000− 100 + 1,100

500 + 500

Sample answers:

+1,000

+700−3,000

−300

1,000

500

30

2

13 3 9 12

45

25 ?

20

10

EM3MJ1_G3_U02_30-54.indd 46 4/2/10 10:54 AM

Math Journal 1, p. 46

Student Page

Name Date Time

The Partial-Sums Addition MethodHOME LINK

2�7

Today your child learned about adding two 3-digit numbers using a procedure called thepartial-sums method. Your child may choose to use this method or may prefer a differentprocedure. For more information, see pages 57 and 58 in the Student Reference Book.

Please return this Home Link to school tomorrow.

FamilyNote

57 58

Solve each addition problem. You may want to use the partial-sums method. Use a ballpark estimate to check that your answer makes sense. Write a number model to show your estimate. Sample estimates given.

1. Ballpark estimate:

4. Ballpark estimate:

2. Ballpark estimate:

5. Ballpark estimate:

3. Ballpark estimate:

6. Ballpark estimate:

250 � 100 � 350

400 � 200 � 600 460 � 200 � 660 800 � 400 � 1,200

100 � 200 � 300 250 � 300 � 550

124� 2152 4 5

� 9 2

100s 10s 1s 245� 317

366� 208

459� 168

769� 445

337

574 627 1,214

339 562

Math Masters, p. 52

Home Link Master

EM3cuG3TLG1_136-140_U02L07.indd 139EM3cuG3TLG1_136-140_U02L07.indd 139 12/30/10 11:57 AM12/30/10 11:57 AM

140 Unit 2 Adding and Subtracting Whole Numbers

3 Differentiation Options

READINESS INDEPENDENTACTIVITY

� Modeling 2-Digit Numbers 5–15 Min

with Base-10 Blocks(Math Masters, p. 411)

To explore place-value concepts using a concrete model, have children build numbers with base-10 blocks. Children draw two cards and place them on a Place-Value Mat to make a 2-digit number. They put longs in the tens column to show the tens digit and cubes in the ones column to show the ones digit. On a half-sheet of paper, children draw a picture to show what they did. They write the number in standard notation and in expanded notation under the picture. (See margin.)

ENRICHMENT SMALL-GROUP ACTIVITY

� Making Up Addition 5–15 Min

Problems from a Mileage Map(Student Reference Book, pp. 224 and 225; Math Masters, p. 407)

Social Studies Link To apply children’s understanding of addition, have them write and solve addition number

stories. Children study the U.S. mileage map in the Student Reference Book, on pages 224 and 225. Pose

problems like the following to be sure that children understand how to read the map.● Find Minneapolis, Minnesota. Which city on the map is 501

miles from Minneapolis? Bismarck, North Dakota

● Find Seattle, Washington. How would you determine the number of miles from Seattle to Salt Lake City, Utah, by way of Boise, Idaho? Add the distance from Seattle to Boise to the distance from Boise to Salt Lake City. Children pose new addition problems to each other using the mileage map. Children may record one or two of their stories on Math Masters, page 407.

ELL SUPPORT SMALL-GROUP ACTIVITY

� Building a Math Word Bank 5–15 Min

(Differentiation Handbook, p. 132)

To provide language support for estimation, have children use the Word Bank template found on Differentiation Handbook, page 132. Ask children to write the term ballpark estimate, draw a picture representing the term, and write other related words. See the Differentiation Handbook for more information.

NOTE The numbers indicate distances

between cities based on routes usually

followed by motorists, except for Hawaii and

Alaska, which are distances by air.

30 + 4 = 34

EM3cuG3TLG1_136-140_U02L07.indd 140EM3cuG3TLG1_136-140_U02L07.indd 140 12/30/10 11:57 AM12/30/10 11:57 AM