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 perimeter of a 5 m by 3 m rectangle is 15 meters.
Corrected: The perimeter of a 5 m by 3 m rectangle is 16 meters.
Grade 4 perimeter = 2L + 2W = 2(5) + 2(3) = 10 + 6 = 16 m.
2. Fix the sentence:
A square with side 6 ft has perimeter 12 feet.
Corrected: A square with side 6 ft has perimeter 24 feet.
Grade 4 square perimeter = 4 x side = 4 x 6 = 24 ft.
3. Fix the sentence:
A rectangle 7 in by 2 in has perimeter 14 square inches.
Corrected: A rectangle 7 in by 2 in has perimeter 18 inches.
Grade 4 perimeter = 2(7) + 2(2) = 18 inches; perimeter is a length, not an area.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. A rectangle with length 8 cm and width 5 cm has perimeter 26 centimeters.
Grade 4: 2(8) + 2(5) = 16 + 10 = 26 cm.
2. A square with side 9 ft has perimeter 36 feet.
Grade 4 square perimeter = 4 x 9 = 36 ft.
3. A rectangle 12 m by 4 m has perimeter 32 meters.
Grade 4: 12 + 4 + 12 + 4 = 32 m.
4. A rectangle 10 in long and 7 in wide has perimeter 34 inches.
Grade 4: 2(10) + 2(7) = 20 + 14 = 34 in.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Explain in your own words how to find the perimeter of a rectangle in Grade 4.
Sample answer: To find the perimeter, add the lengths of all four sides. For a rectangle, you can use 2L + 2W. For example, a 9 m by 4 m rectangle has perimeter 2(9) + 2(4) = 18 + 8 = 26 meters.
Grade 4 perimeter is the total distance around a shape, measured in regular units.
2. Why is perimeter measured in regular units like meters, but area is measured in square meters?
Sample answer: Perimeter is a single length all the way around a shape, so it uses one-dimensional units like meters. Area covers a flat surface using unit squares, so it needs two-dimensional units called square meters.
Grade 4 students must distinguish length units from square units when labeling answers.