areas of rectangles - everyday math · 722 unit 9 coordinates ... • use a formula to calculate...

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722 Unit 9 Coordinates, Area, Volume, and Capacity

Advance PreparationFor Part 1, display a set of unit squares. (See Planning Ahead, Lesson 9-2.) Use a roll of paper or foil

to demonstrate carpet rolls for Math Journal 2, page 305, Problem 2.

Teacher’s Reference Manual, Grades 4–6 pp. 220 –222, 233, 234, 236

Key Concepts and Skills• Multiply fractions and mixed numbers

to find the area of a rectangle.

[Operations and Computation Goal 5]

• Use a formula to calculate the areas

of rectangles.

[Measurement and Reference Frames Goal 2]

• Compare inch and centimeter measures

for length and area.


Key ActivitiesStudents review area concepts and the

names and notations for common area

units. They find areas of rectangles by

counting and by applying an area formula.

Ongoing Assessment: Informing Instruction See page 725.

Ongoing Assessment: Recognizing Student Achievement Use an Exit Slip (Math Masters,page 414). [Measurement and Reference

Frames Goal 2]

Key Vocabularyarea � square units � base � height �

formula � variable

MaterialsMath Journal 2, pp. 304 and 305

Student Reference Book, p. 188

Study Link 9�3 � Math Masters, p. 414

transparency of Math Masters, p. 436 � Class

Data Pad � inch ruler � slate � roll of paper

towels, wax paper, or aluminum foil (optional)

Fraction Division ReviewMath Journal 2, p. 306

Student Reference Book, pp. 80–80B

Students use visual models and

number stories to solve fraction

problems.

Math Boxes 9�4Math Journal 2, p. 307

Students practice and maintain skills

through Math Box problems.

Study Link 9�4Math Masters, p. 265

Students practice and maintain skills

through Study Link activities.

READINESS

Comparing Perimeter and AreaMath Masters, p. 266

per partnership: 2 six-sided dice,

36 centimeter cubes

Students use centimeter grids to compare

the perimeters and areas of rectangles.

ENRICHMENTComparing Perimeter and Area for Irregular FiguresMath Masters, pp. 267 and 436

3 different-colored pencils or markers �

scissors

Students compare the perimeters and

areas of irregular polygons.

EXTRA PRACTICE

5-Minute Math5-Minute Math™, p. 212

Students calculate the areas of rectangles.

EXTRA PRACTICE

Area: Tiling and Using a FormulaMath Masters, pp. 293A and 436

Students find the areas of rectangles with

fractional units by tiling and using a formula.

ELL SUPPORT

Building a Math Word BankDifferentiation Handbook, p. 142

Students define and illustrate the terms

length, height, base, and width.

Teaching the Lesson Ongoing Learning & Practice Differentiation Options

Areas of RectanglesObjective To reinforce students’ understanding of area

concepts and units of area. c

��

eToolkitePresentations Interactive Teacher’s

Lesson Guide

Algorithms Practice

EM FactsWorkshop Game™

AssessmentManagement

Family Letters

CurriculumFocal Points

Common Core State Standards

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Student Reference Book, p. 188

Student Page

Area

Area is a measure of the amount of surface inside a closedboundary. You can find the area by counting the number ofsquares of a certain size that cover the region inside theboundary. The squares must cover the entire region. They mustnot overlap, have any gaps, or extend outside the boundary.

Sometimes a region cannot be covered by an exact number ofsquares. In that case, count the number of whole squares andfractions of squares that cover the region.

Area is reported in square units. Units of area for small regionsare square inches (in.2), square feet (ft2), square yards (yd2),square centimeters (cm2), and square meters (m2). For largeregions, square miles (mi2) are used in the United States, whilesquare kilometers (km2) are used in other countries.

You may report area using any of the square units. But youshould choose a square unit that makes sense for the regionbeing measured.

Although each of the measurements above is correct, reportingthe area in square inches really doesn’t give a good idea aboutthe size of the field. It is hard to imagine 7,776,000 of anything!

Measurement

ExamplesExamples The area of a field-hockey field is reported below in three different ways.

Area of the field is 6,000 square yards.

Area � 6,000 yd2

Area of the field is 54,000 square feet.

Area � 54,000 ft2

Area of the field is7,776,000 square inches.

Area � 7,776,000 in.2

100 yd

60 yd

300 ft

180 ft

3,600 in.

2,160 in.

1 cm

1 cm

1 square centimeter(actual size)

1 in.

1 in.

1 square inch(actual size)

The International SpaceStation (ISS) orbits theEarth at an altitude of250 miles. It is 356 feetwide and 290 feet long,and has an area of over100,000 square feet.

Lesson 9�4 723

Getting Started

1 Teaching the Lesson

▶ Math Message Follow-Up WHOLE-CLASSDISCUSSION

(Student Reference Book, p. 188)

Ask volunteers to share what they wrote about area. Use their responses and the display of common units of area to review basic area concepts. Emphasize the following points:

� Area is a measure of the surface, or region, inside a closed boundary. It is the number of whole and partial unit squares needed to cover the region without gaps or overlaps.

NOTE It is more precise to talk about the area of a rectangular region, the

area of a triangular region, and so on. However, it is customary to refer to area

in terms of the figure that is the boundary: the area of a rectangle, the area of a

triangle, and so on.

� Area is measured in square units. There are many units to choose from, and some choices make more sense than others.

Call students’ attention to the classroom display of unit squares and to alternative ways of writing the units: square inch, sq in., or in2; square meter, sq m, or m2; and so on.

Ask students to share the relationships they observe among the units—for example, a square meter is larger than a square yard. There are 9 square feet in a square yard and 144 square inches in a square foot. A square inch is larger than a square centimeter.

Mental Math and ReflexesHave students write fractions as equivalent decimals and percents. Suggestions:

2

_ 3 0. ⎯⎯ 66 ; 66

2

_ 3 %

4

_ 5 0.8; 80%

8

_ 25

0.32; 32%

19

_ 20

0.95; 95%

24

_ 50

0.48; 48%

3

_ 8 0.375; 37.5%

Math MessageRead page 188 of the Student Reference Book, and write two important facts about area.

Study Link 9�3 Follow-UpHave partners compare answers and resolve any differences.

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Math Journal 2, p. 304

Student Page

Areas of RectanglesLESSON

9�4

Date Time

1. Fill in the table. Draw rectangles D, E, and F on the grid.

2. Write a formula for finding the area of a rectangle.

Area =

1 cm2 1 cm

1 cm

he

igh

t(o

r w

idth

)

base(or length)

A

B

C

D

E

F

Rectangle Base (length) Height (width) Area

A 2 cm

5 cm 10 cm2

B 4 cm

4 cm 16 cm2

C 2.5 cm

2.5 cm 6.25 cm2

D 6 cm 2 cm 12 cm2

E 3.5 cm 4 cm 14 cm2

F 3 cm 3.5 cm 10.5 cm2

base ∗ height (b ∗ h), or length ∗ width (l ∗ w)

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▶ Finding the Area of a Rectangle PARTNER ACTIVITY

(Math Journal 2, p. 304)

Ask volunteers to define the terms base and height. The term base is often used to mean both a side of a figure and the length of that side. The height of a rectangle is the length of a side adjacent to the base.

Ask students to decide upon the phrasing of a common definition for these vocabulary terms. Record the student definitions on the Class Data Pad.

Ask a volunteer to draw a rectangle on the board and label the base and height.

base

height

In Fourth Grade Everyday Mathematics, students found the area of a rectangle by counting unit squares. Then they developed a formula for finding the area of a rectangle. Expect that students might use either method—formula or counting squares—to find the areas of the rectangles on journal page 304.

With the counting method, some rectangles enclose partial grid squares, and students must count and add the full and partial squares to find areas. For example, rectangle C encloses 4 full squares (4 cm2), 4 half-squares (4 ∗ 1 _ 2 = 2 cm2), and 1 quarter-square ( 1 _ 4 cm2). Its total area is 4 + 2 + 1 _ 4 = 6 1 _ 4 cm2.

4 full squares 4 cm2

4 half-squares 2 cm2 Each half-square has an area of 1 _ 2 cm2.

+1 quarter-square 1 _ 4 cm2 The quarter-square is 1 _ 2 cm long and 1 _ 2 cm wide.

total area 6 1 _ 4 cm2

1 cm2 1 cm

1 cm

C

Assign journal page 304, Problem 1. Circulate and assist.



Student Page

Area ProblemsLESSON

9 � 4

Date Time

1. A bedroom floor is 12 feet by 15 feet

(4 yards by 5 yards).

Floor area =

square feet

Floor area = square yards

2. Imagine that you want to buy carpet for

the bedroom in Problem 1. The carpet

comes on a roll that is 6 feet (2 yards)

wide. The carpet salesperson unrolls the

carpet to the length you want and cuts

off your piece. What length of carpet

will you need to cover the bedroom floor?

3. Calculate the areas for the 4. Fill in the missing lengths for

figures below. the figures below.

Area = yd2

Area = ft2

180

20

72

76

a.

b.

a.

b.

15 ft (5 yd)

12 ft

(4 yd)

6 ft

(2 yd)

9 yd

6 yd

6 yd6 y

d

12 y

d

3 yd

4 f

t

8 ft

2 ft124 ft

1212 ft

12 ft

360 ft2

12

30 ft 30 ft

ft

25 yd375 yd225 yd

15 yd

15 yd

30 ft, or 10 yd

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Lesson 9�4 725

▶ Discussing Formulas for WHOLE-CLASSDISCUSSION

the Area of a Rectangle(Math Journal 2, p. 304; Math Masters, p. 436)

Algebraic Thinking Ask volunteers to give the dimensions of rectangles A–F as other volunteers draw the rectangles on a transparency of Math Masters, page 436.

Ask: What do you notice about the relationship between the base and height and the actual area of each figure? The base multiplied by the height is equal to the area.

Reinforce this rule:

If the length of the base and the height of a rectangle are known, the area can be found by multiplying the length of the base by the height.

Such a rule is called a formula. The formula can be written in abbreviated form as:

A = b ∗ h,

where A stands for the area, b stands for the length of the base, and h stands for the height. Ask students to complete Problem 2 on journal page 304. Remind students that letters used in this way are called variables. Add the abbreviated formula to the definitions on the Class Data Pad, and have students write the abbreviated formula after their answers for Problem 2 on journal page 304.

Refer students to the rectangles drawn on the transparency. Have students apply the formula for the rectangles in Problem 1. Ask volunteers to record a number model for the area of each rectangle on the transparency. For example, 2 cm ∗ 5 cm = 10 cm2. Have students check their total count of the squares with the product from the number model. For rectangles C and E, ask students to think about the decimals as fractions (2 1 _ 2 cm ∗ 2 1 _ 2 cm = 6 1 _ 4 cm2, and 4 cm ∗ 3 1 _ 2 cm = 14 cm2).

Ask partners to estimate, in inches, the length of the sides of the rectangles on journal page 304. Then have students measure the sides of rectangle C using their inch rulers. (Each side of rectangle C is about 1 inch long.) Ask students what the area of rectangle C is when the unit is inches. 1 square inch Point out that there are about 2.5, or 2 1 _ 2 centimeters in 1 inch, and about 6.25, or 6 1 _ 4 square centimeters in 1 square inch.

▶ Applying the Area Formulas

INDEPENDENT ACTIVITY


Have students complete journal page 305. Circulate and assist.

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BBBBBBBBBBBBBBBBBBBB EEELEMMMMMMMMOOOOOOOOOBBBBLBLBLBLBBOOOOROROROROROROROROROO LELELELEEEEEELEMMMMMMMMMMMMMLEMLLLLLLLLLLLLLLLLLLLLLLRRRRRRRRRRRGGGLLLLLLLLLLLVINVINVINVINNNNVINVINNVINVINVINVINVINVV GGGGGGGGGGGOLOOOLOOLOLOLOO VINVINVVINLLLLLLLLLVINVINVINVINVINVINVINVINVINVINVINVINV NGGGGGGGGGGOOOLOLOLOLOLOLOOO VVVVVVLLLLLLLLLLVVVVVVVVOOSOSOOSOSOSOSOSOSOSOOSOSOSOSOSOOOOOSOSOSOSOSOSSOOSOSOSOSOSOSOSOSOSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS VVVVVVVVVVVVVVVVVVVVVVVLLLLLLLVVVVVVVVVLLVVVVVVLLLLLLLLVVVVVLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLSSSSSSSSSSSSSSSSSSSSSSS GGGGGGGGGGGGGGGGGGOOOOOOOOOOOOOOOOOOO GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGNNNNNNNNNNNNNNNNNNNNNNNNNNNIIIIIIIIIIIIIIIIIIIIISOLVING

NOTE An alternative formula for the area of

a rectangle is A = l ∗ w, where l stands for

the length and w stands for the width of the

rectangle. Students are familiar with both

versions of the formula from Fourth Grade

Everyday Mathematics.

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Student Page

Fraction Division ReviewLESSON

9 � 4

Date Time

J

J

J

L L

L

M

M

M

1. Liz, Juan, and Michael equally share 9

_ 12 of a pizza.

a. To show how the 9 pieces can be distributed,

write the student’s initial on each piece that he

or she is getting.

b. Each student will get pieces.

c. Write a number model to show what fraction

of the whole pizza each student gets.

2. A football team orders a 6-foot-long submarine sandwich. Each player

will eat 1 _ 3 of a foot of sandwich. Draw tick marks on the ruler to help you

find how many players the sandwich will serve.

0 FEET 1 2 3 4 5 6

The sandwich will serve players. So, 6 ÷ 1

_ 3 = .

3. When Mr. Showers won a large amount of money, he donated half to a local

college. The funds were divided equally among 5 departments.

a. Write an open number model to show how much of

Mr. Shower’s prize went to each department.

b. Each department received of the prize.

4. The stone is a unit of weight used in the United Kingdom

and Ireland. One pound equals 1 _ 14 stone. Anna’s pen pal

in Ireland weighs 6 stones. How much is this in pounds? pounds

5. Write a number story that can be solved by dividing 3 by 1 _ 4 . Solve your problem.

3

9

_ 12 ÷ 3 = 3

_

12 , or 1 _

4

18 18

1

_ 10

1 _

2 ÷ 5 = p

84

Answers vary.

292-332_EMCS_S_MJ2_G5_U09_576434.indd 306 4/6/11 11:01 AM

Date Time

5. Write true or false.

a. 5,278 is divisible by 3. false

b. 79,002 is divisible by 6. true

c. 86,076 is divisible by 9. true

d. 908,321 is divisible by 2. false

6. Complete the “What’s My Rule?” table,

and state the rule.

Rule: ∗ 2 + 1

1. A rope 3

_ 4 meter long is cut into 6 equal pieces.

meters

a. Draw lines on the rope to show how

long each piece will be.

b. Write a number model to describe

the problem.

3. Compare. Use <, >, or =.

a. 8 * 105 > 80,000

b. 12.4 million = 12,400,000

c. 7,000,000 > 7 * 105

d. 82 < 28

e. 5.4 * 102 < 5,400

4. Solve.

a. 429 b. 134

* 15 * 82

c. 706

*189

2. What is volume of the prism?

Choose the best answer.

240 units3

90 units2

30 units3

90 units3

6,435 10,988

133,434

in out

4 9

7 15

11 23

9 19

6 13231 232

220 221 19 20

80A 80B

11

197

Math Boxes LESSON

9 � 4

340 1

3

_ 4 ÷ 6 =

1

_ 8

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Student Page


Ongoing Assessment: Informing Instruction

Watch for students who hesitate with Problem 2. Ask: Which unit makes more

sense to work with, feet or yards? yards Refer students to Problem 1 and ask

how many yards of carpet are needed. 20 square yards Illustrate Problem 2

using a roll of paper towels, waxed paper, or aluminum foil to demonstrate how a

piece of carpet is cut from a roll. As the “carpet” unrolls, the area increases. For

example, in Problem 2, each foot unrolled adds an additional 6 square feet or 2

square yards. As you unroll the model, have students shade the grid in Problem

1 to show how much floor is covered. Prompt students to tell you where to cut

the model.

When most students have completed the journal page, ask volunteers to share their solution strategies. Ask questions like the following:

● In Problem 2, how will you cut the carpet to make it fit the bedroom? If students determine that they will need a piece of carpet 30 feet or 10 yards long, they will need to cut it in half to fit the bedroom. Each of the two pieces will be 2 yards by 5 yards.

2 yd

10 yd

5 yd

4 yd2 yd

2 yd

● In Problem 4, how did you find the missing lengths? Encourage students to use multiplication/division relationships and open number sentences. For example, 360 ÷ 12 = h, or 25 ∗ b = 375.

Ongoing Assessment: Exit Slip�Recognizing Student Achievement

Use an Exit Slip (Math Masters, page 414) to assess students’ ability to

calculate area. Have students write a response to the following: Explain how you

found the area for the figure in Problem 3b on journal page 305. Students are

making adequate progress if they multiply the side lengths to find the areas of the

rectangles in order to find the total area.



Math Masters, p. 265

Study Link Master

STUDY LINK

9 �4 More Area Problems

104 105189

Name Date Time

1. Rashid can paint 2 square feet of fence in 10 minutes. Fill in the

missing parts to tell how long it will take him to paint a fence

that is 6 feet high by 25 feet long. Rashid will be able to paint

of fence in .

2. Regina wants to cover one wall of her room with wallpaper. The wall is

9 feet high and 15 feet wide. There is a doorway in the wall that is 3 feet

wide and 7 feet tall. How many square feet of wallpaper will she need to buy?

Calculate the areas for the figures below.

3. 4.

Area = yd2 Area = ft2

Fill in the missing lengths for the figures below.

5. 6.

150 sq ft 12 hr 30 min

3380

(hours/minutes)(area)

4 yd

10 yd

4 yd

4 yd

12 yd

1 ft

5 ft

2 ft

4 ft

2 ft

9 ft

50 cm

3,000 cm2

50 cm

60 cm60 cm6 m198 m2

33 m

33 m

6 m

114 square feet

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Teaching Master

LESSON

9 �4

Name Date Time

Comparing Perimeter and Area

� Roll 2 six-sided dice. The numbers on top

are the lengths of 2 sides of a rectangle.

� Draw the rectangle in the grid below.

� Record the perimeter and the area

of the rectangle in the table.

� Use centimeter cubes to find other

rectangles that have the same area,

but different perimeters. Draw the

rectangles and record their perimeters

and areas in the table.

� Repeat until you have filled the table. You

might need to roll the dice several times.

Rectangle Perimeter Area

A

B

C

D

E

F

Answers vary.


Lesson 9�4 727

2 Ongoing Learning & Practice

▶ Fraction Division Review PARTNER ACTIVITY

(Math Journal 2, p. 306; Student Reference Book, pp. 80–80B)

Have students review information about fraction division problems on pages 80–80B of the Student Reference Book. Discuss the use of visual models and number stories. Then have students complete the journal page.

▶ Math Boxes 9�4



Mixed Practice Math Boxes in this lesson are paired with Math Boxes in Lesson 9-2. The skill in Problem 6 previews Unit 10 content.

Writing/Reasoning Have students write a response to the following: Explain how you could determine the volume of the rectangular prism in Problem 2 by counting the unit

cubes. Then write a number model for the formula you could use to find the volume. Sample answers: I could count the number of unit cubes in the bottom layer first. The width is 6 and the length of the base is 5. So there are 30 unit cubes in the bottom layer. The height is 3, so there are three layers of 30. The volume is 90 units3. The formula is B ∗ h = V. The number model is (5 ∗ 6) ∗ 3 = 90 units3.

▶ Study Link 9�4


(Math Masters, p. 265)

Home Connection Students solve area problems.

3 Differentiation Options

READINESS PARTNER ACTIVITY

▶ Comparing Perimeter and Area 5–15 Min

(Math Masters, p. 266)

To support students’ understanding of perimeter and area, have partners roll 2 six-sided dice to determine the dimensions of a rectangle. They draw a rectangle with those dimensions and find the perimeter and area of the rectangle. Partners then find other rectangles with the same area, but different perimeters. They repeat this process until the table on page 266 is completed.

Discuss what conclusions can be drawn from the table. Sample answers: Different perimeters can have the same area; the dimensions are factor pairs for the area.


py

gg

p

LESSON

9 �4

Name Date Time

Perimeter and Area of Irregular Figures

� Cut 6 rectangles that are 6 columns by 7 rows from the centimeter grid paper.

� Record the area and the perimeter of one of these rectangles in Problem 1.

� Divide each rectangle by using 3 different colored pencils to shade three connected parts

with the same number of boxes. The parts must follow the grid, and the squares must be

connected by sides.

� Divide each rectangle in a different way.

1. For a rectangle that is 6 cm by 7 cm:

Area = Perimeter =

2. Record the perimeters for the divisions of the 6 rectangles in the table.

3. What is the area for each of the parts?

4. What is the range of the perimeters for each of the parts?

5. a. Describe one relationship between perimeter and area.

b. Is the relationship the same for rectangles and irregular figures? Explain.

Perimeters

Rectangle

Part 1 Part 2 Part 3

1

2

3

4

5

6

Answers vary.

26 cm42 cm2

14 square centimeters

Answers vary.

Sample answer: Shapes with the same area can have different perimeters.

Answers vary.



Teaching Master

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gg

p

LESSON

9�4

Name Date Time

Area: Tiling and Using a Formula

For each rectangle below, cut out a rectangle from the centimeter grid paper (Math Masters,

page 436) that has the same dimensions. Follow the directions for each problem.

1. The length of the base of the rectangle

is 6 cm and the height is 2 1

_ 2 cm.

a. Tape the centimeter grid over the rectangle, and then

use the counting method to find the area of the rectangle. 15 cm2

b. Use the formula to write an open number

model that can be used to find the area. 6 ∗ 2

1

_ 2 = A

c. Area = 15 cm2

2. The length of the base of the rectangle below is 12 1

_ 2 cm and the height is 2

1

_ 2 cm.


use the counting method to find the area of the rectangle. 31

1

_ 4 cm2

b. Use the formula to find the area. 31

1

_ 4 cm2

3. a. Use the formula to find the area of the rectangle below. 15

3

_ 4 cm2

b. Tape the centimeter grid over the rectangle, and then

use the counting method to find the area of the rectangle. 15

3

_ 4 cm2

c. Explain why the formula and the counting method produce the same area.

Sample answer: Each row has the same number of squares. So,

multiplying the base by the height gives you the number of squares

there are in all. Counting the squares gives you the same area.

10 1

_ 2 cm

1 1

_ 2 cm

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Math Masters, p. 293A

Teaching Master


ENRICHMENT PARTNER ACTIVITY

▶ Comparing Perimeter and 15–30 Min

Area for Irregular Figures(Math Masters, pp. 267 and 436)

To apply students’ understanding of perimeter and area to irregular figures, have partners divide rectangles and compare the relationship between perimeter and area. When students have finished, have them share the parts they cut from their rectangles and discuss questions such as the following:

● Can you use the area of a figure to predict the perimeter of that figure? No

● Can you use the perimeter of a figure to predict the area of that figure? No

Guide students to conclude that perimeter and area are independent measures.

EXTRA PRACTICE

SMALL-GROUP ACTIVITY

▶ 5-Minute Math 5–15 Min

To offer students more experience with calculating the area of rectangles, see 5-Minute Math, page 212.

EXTRA PRACTICE PARTNER ACTIVITY

▶ Area: Tiling and Using 15–30 Min

a Formula(Math Masters, pp. 293A and 436)

To find the area, students use grid paper to tile rectangles that have fractional side lengths. They also use the formula for the area of a rectangle to show that both methods produce the same result.

ELL SUPPORT

SMALL-GROUP ACTIVITY

▶ Building a Math Word Bank 5–15 Min

(Differentiation Handbook, p. 142)

To provide language support for area, have students use the Word Bank Template found on Differentiation Handbook, page 142. Ask students to write the terms length, height, base, and width; draw pictures relating to each term; and write other related words. See the Differentiation Handbook for more information.


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ht ©

Wrig

ht G

roup/M

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raw

-Hill

LESSON

9�4

Name Date Time

Area: Tiling and Using a Formula

293A

For each rectangle below, cut out a rectangle from the centimeter grid paper (Math Masters,

page 436) that has the same dimensions. Follow the directions for each problem.

1. The length of the base of the rectangle

is 6 cm and the height is 2 1

_ 2 cm.


use the counting method to find the area of the rectangle. cm2

b. Use the formula to write an open number

model that can be used to find the area.

c. Area = cm2

2. The length of the base of the rectangle below is 12 1

_ 2 cm and the height is 2

1

_ 2 cm.



b. Use the formula to find the area. cm2

3. a. Use the formula to find the area of the rectangle below. cm2

b. Tape the centimeter grid over the rectangle, and then


c. Explain why the formula and the counting method produce the same area.

10 1

_ 2 cm

1 1

_ 2 cm

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areas of rectangles - everyday math · 722 unit 9 coordinates ... • use a formula to calculate...

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