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:
A regular pentagon with each side measuring 4 cm have a perimeter of 20 cm.
Corrected: A regular pentagon with each side measuring 4 cm has a perimeter of 20 cm.
The singular subject pentagon takes the singular verb has in this Grade 4 sentence.
2. Fix the sentence:
To find perimeter of an irregular shape, you adds every side length together.
Corrected: To find the perimeter of an irregular shape, you add every side length together.
With you, the verb stays as add, and the article the is needed before perimeter.
3. Fix the sentence:
The hexagons sides was each 5 inches long, giving a perimeter of 30 inches.
Corrected: The hexagon's sides were each 5 inches long, giving a perimeter of 30 inches.
Hexagon's shows possession, and sides is plural so it pairs with the verb were.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. A regular pentagon has 5 equal sides of 4 cm, so its perimeter is 20 cm.
All five sides match, so 5 x 4 equals 20 cm for the total perimeter.
2. A regular hexagon has 6 equal sides that we add to find perimeter.
A hexagon has six sides, so we add or multiply six side lengths for perimeter.
3. An irregular shape with sides 3, 4, 5, and 6 cm has a perimeter of 18 cm.
Adding 3 + 4 + 5 + 6 gives 18, the total distance around the irregular shape.
4. Perimeter is measured in length units like inches, feet, or centimeters.
Perimeter is a single line distance, so we use length units, not square units.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Describe how to find the perimeter of an irregular shape with five different side lengths.
Sample answer: I list every side length first so I do not miss any. Then I add all five numbers together using column addition. The total sum is the perimeter, and I label it with the correct length unit, such as cm or inches, in my Grade 4 answer.
Irregular shapes have different sides, so addition of each side is the safest Grade 4 method.
2. How can you use multiplication to find the perimeter of a regular hexagon?
Sample answer: A regular hexagon has six equal sides. Instead of adding the same number six times, I multiply one side by 6. For example, if a side is 7 cm, I find 7 x 6, which equals 42 cm. Multiplication is faster than repeated addition.
Regular polygons have identical sides, so multiplying side by number of sides saves time.