# 4th Grade - Area Of Rectangles In Square Units

 Grade Level: 4th Skill: Area and Perimeter Topic: Area of Rectangles in Square Units Goal: Measure the area of rectangular shapes by using appropriate units, such as square centimeter (cm2), square meter (m2), square kilometer (km2), square inch (in.2) square yard (yd.2) or square mile (mi.2) Skill Description: Measure the area of rectangles by multiplying length x width. (A = l x w). Ensuring that units are displayed after the measurement.

## Building Blocks/Prerequisites

### Sample Problems

(1)

What is the area of the figure:

Length = ___ Width = ___

Area = _________ cm2

(7 x 4 = 28 cm2)

(2)

Find the area of the square:

Area = _____ yd.2

(64 yd2)

(3)

Find the area of the rectangle:

Area = _______mi.2

(50 mi2)

(4)

Find the area of the polygon:

Area = _______ m2

(4 x 7= 28; 9 x 3 = 27; 27 + 28 = 55 m2)

(5)

Draw a figure with an area of 45 cm.2 Area ____ x ____ = 45 cm2

(Drawings will vary—9 x 5; 45 x 1; 15 x 3)

(6)

Use and interpret formulas (i.e. area = length x width or A = lw) to answer questions about quantities and their relationships. (4)

### Learning Tips

(1)

Place the shape on a grid and have child count the squares. Let them know that is the area for the figure.

Then, have them count the number of squares across (5) and the number of squares down (4). Multiply the numbers and it will also equal the area A = 5 x 4 = 20.

(2)

Review the formula for area and explain:

Area = Length x Width (A= l x w)

(3)

Math vocabulary:

Area- the number of square units needed to cover a surface

Plane figures- a closed figure that lies on a flat surface and is all in one plane

Square unit- a square with a side length of one unit; used to measure area.

Polygon- A closed plane figure with straight sides (most shapes, except for circle, oval, and other non-straight line figures).

(4)

Divide figure to find area:

Example

 4 4 7 3 3 7

Divide the polygon into two rectangles. The larger rectangle measures as (4) length and (7) at the width. Use the formula for finding the rectangle (A = l x w) A = 4 x 7 = 28. Next, find the area of the smaller square which is (3) length and (3) width. A= 3 x 3 = 9. Finally, add the two areas together 28 + 9 = 37 sq. units.

(5)

Geo-board/ Dot Paper

Have the child practice drawing shapes and counting the number of squares it covers on the inside. Inform them that the number of squares it covers is the area in square units.

### Extra Help Problems

(1)

Find the area of the rectangle: Area = ________

(2)

Find the area of the rectangle: Area = ________

(3)

Find the area of the square: Area = ________ cm 2

(9 cm 2)

(4)

Find the area of the rectangle: Area = ________ m 2

(56 m 2)

(5)

Find the missing measurement: Area = 16 in 2

(4 in)

(6)

Find the missing measurement: Area = 24 cm 2

(8 cm)

(7)

Find the missing measurement: Area = 36 cm 2

(6 cm)

(8)

Find the missing measurement: Area = 144 in 2

(72 in)

(9)

Find the missing measurement: Area = 75 ft 2

(25 ft)

(10)

Find the area of the square: Area = ________ m 2

(100 m 2)

(11)

Find the area of the rectangle: Area = ________

(27 in 2)

(12)

Find the area of the polygon: Area = ________ in 2

Hint: Separate the two rectangles and find the areas, then add them together

(12 x 5 = 60; 15 x 6 =90; 60 +90 =150 in 2)

(13)

Find the area of the polygon: Area = _________ m 2

Hint: Separate the two rectangles and find the areas, then add them together.

(4 x 18 = 72; 10 x 8 = 80; 72 + 80 = 152 m 2)

(14)

Find the area of the rectangle: A = _____ ft 2

(32 ft 2)

(15)

Find the area of the square: A = ____ mi 2

(324 mi 2)

(16)

Find the area of the rectangle: A=_____ cm 2

(2,958 cm 2)

(17)

Find the area of the rectangle: A = ________ ft 2

(952 ft 2)

(18)

Find the area of the rectangle: A = _____ in 2

(637 in 2)

(19)

Find the area of the rectangle: A = _____ m 2

(2,814 m 2)

(20)

Write the formula to find the area for the figure:

Area = ____ x ____ = ______sq. units

(5 x 11 = 55 sq. units)

(21)

Write the formula to find the area for the figure:

Area = ____ x ____ = ______sq. units

(2 x 12 = 24 sq. units)

(22)

Write the formula to find the area for the figure:

Area = ____ x ____ = ______sq. units

(6 x 13= 78 sq. units)

(23)

Shade the area of a figure that is: 24 sq. units

Area = ____ x ____ = 24 sq. units

(Answers will vary—2 x 12; 3 x 8; 4 x 6; 1 x 24)

(24)

Shade the area of a figure that is: 84 sq. units

Area = _____ x _____ = 84 sq. units

(Answers will vary—42 x 2; 21 x 4; 14 x 6; 84 x 1)