Area and Perimeter (Advanced) — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
The area of a 5 ft by 3 ft rectangle is 8 square feet.
Corrected: The area of a 5 ft by 3 ft rectangle is 15 square feet.
For Grade 4, area = length x width. So 5 x 3 = 15 square feet, not 5 + 3.
2. Fix the sentence:
A square with side 4 cm has an area of 16 cm.
Corrected: A square with side 4 cm has an area of 16 square cm.
Grade 4 students must label area with square units like sq cm because area covers a 2D surface.
3. Fix the sentence:
A rectangle 7 in by 2 in has area 9 square inches.
Corrected: A rectangle 7 in by 2 in has area 14 square inches.
Grade 4 area is L x W. 7 x 2 = 14 square inches, not 7 + 2 = 9.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. A rectangle with length 6 m and width 4 m has area 24 square meters.
Grade 4 area = L x W = 6 x 4 = 24 sq m.
2. A square with side 5 ft has area 25 square feet.
Grade 4 square area = side x side = 5 x 5 = 25 sq ft.
3. A rectangle 9 cm long and 3 cm wide has area 27 square centimeters.
Grade 4 area = 9 x 3 = 27 sq cm.
4. A rectangle 8 in by 6 in has area 48 square inches.
Grade 4 area = 8 x 6 = 48 sq in.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Explain in your own words how to find the area of a rectangle in Grade 4.
Sample answer: To find the area of a rectangle, multiply the length by the width. For example, a rectangle 7 ft long and 4 ft wide has an area of 7 x 4 = 28 square feet. Always label the answer with square units.
Grade 4 students must remember area = length x width and use square units.
2. A garden is 10 m long and 6 m wide. What is the area, and why must the unit be square meters?
Sample answer: The area is 10 x 6 = 60 square meters. Area is measured in square units because it tells how many unit squares cover the garden, so we say square meters, not just meters.
Grade 4 area uses square units to describe a 2D surface covered by unit squares.