Area of Rectangles

Site:	Saylor Academy
Course:	GKT101: General Knowledge for Teachers – Math
Book:	Area of Rectangles

Printed by:	Guest user
Date:	Saturday, May 18, 2024, 6:04 AM

Description

Area is the measurement indicating how much space on a plane is taken up by a two-dimensional shape. While perimeter is measured in units of length, area is measured in square units. We will discuss units of measurement in more detail in the next section. Watch this lecture series about calculating the area of rectangles, and complete the interactive exercises.

Table of contents

Counting unit squares to find area formula
Transitioning from unit squares to area formula
Practice

Counting unit squares to find area formula

Source: Khan Academy, https://www.khanacademy.org/math/cc-third-grade-math/imp-geometry
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License.

Transitioning from unit squares to area formula

Practice

Area of rectangles with partial arrays - Questions

1. The following rectangle is partially split into unit squares.

What is the area of the rectangle above?

_______ square units

2. The following rectangle is partially covered with unit squares.

Which figure has the same area as the rectangle above?

Choose 1 answer:

3.

is 1 unit square.

What is the area of rectangle $A$ ?

_________ square units

4. The following rectangle is partially split into unit squares.

What is the area of the rectangle above?

_________ square units

5. The following rectangle is partially covered with unit squares.

Which figure has the same area as the rectangle above?

Choose 1 answer:

6.

is 1 unit square.

What is the area of rectangle $A$ ?

_________ square units

7. The following rectangle is partially split into unit squares.

What is the area of the rectangle above?

_________ square units

Area of rectangles with partial arrays - Answers

1. $\text { Area }=21 \text { square units }$

2. We would use the same number of unit squares to cover this rectangle, so it would have the same area:

3. $\text { Area }=42 \text { square units }$

4. $\text { Area }=30 \text { square units }$

5. We would use the same number of unit squares to cover this rectangle, so it would have the same area:

6. $\text { Area }=28 \text { square units }$

7. $\text { Area }=32 \text { square units }$

Transition from unit squares to area formula - Questions

1. is 1 unit square.

Which expressions can we use to find the area of the rectangle?

Choose 2 answers:

(A) $5 \times 9 \times 5 \times 9$

(C) $9+9+9+9+9$

(D) $5 \times 9$

2. Which equation shows a way to find the area of the following rectangle?

Choose 1 answer:

(A) 9 units $\times 7$ units $=63$ square units

(B) 6 units $\times 3$ units $=18$ square units

(C) 6 units $\times 8$ units $=48$ square units

(D) 5 units $\times 7$ units $=35$ square units

3. is 1 unit square.

Which expressions can we use to find the area of the rectangle?

Choose 2 answers:

(D) $3 \times 9$

4. Which expression shows a way to find the area of the following rectangle?

Choose 1 answer:

(B) $5+5+5+5+5$

(C) $5 \times 4$

(D) $4 \times 4$

5. is 1 unit square.

Which expressions can we use to find the area of the rectangle?

Choose 2 answers:

(A) $5 \times 7$

(B) $5 \times 5 \times 5 \times 5 \times 5 \times 5 \times 5$

(C) $7+7+7+7+7$

(D) $5 \times 7+5 \times 7$

6. Which equation shows a way to find the area of the following rectangle?

Choose 1 answer:

(A) 9 units $\times 4$ units $=36$ square units

(B) 9 units $+4$ units $=13$ units

(C) 9 units $+3$ units $=12$ units

(D) 9 units $\times 3$ units $=27$ square units

7. is 1 unit square.

Which expressions can we use to find the area of the rectangle?

Choose 2 answers:

(A) $7+7+7+7+7+7+7$

(B) $7 \times 7$

(C) $8 \times 7$

(D) $8+8+8+8+8+8+8$

Transition from unit squares to area formula - Answers

1. We can use these expressions to find the area of the rectangle:

2. The equation $6 \, units \times \, 8 \, units \, = \, 48$ square units shows a way to find the area of the rectangle.

3. We can use these expressions to find the area of the rectangle:

4. The expression $5 \times 4$ shows a way to find the area of the rectangle.

5. We can use these expressions to find the area of the rectangle:

6. The equation 9 units $\times 4$ units $=36$ square units shows a way to find the area of the rectangle.

7. We can use these expressions to find the area of the rectangle: