Perimeter Patrol Worksheet
Perimeter Patrol
Grade 3 Math • ILEARN Practice Review
Name: ______________________________
Date: ________________
Directions: Read each question carefully. Show your work in the blank boxes and double-check your units!
1
Maya drew the pentagon shown below. What is the perimeter of Maya’s pentagon?
6 cm 6 cm 5 cm 5 cm 8 cm
A 19 centimeters
B 24 centimeters
C 30 centimeters
D 32 centimeters
2
Each square on the grid below has a side length of 1 unit. What is the perimeter of the shaded figure?
1 side of a square = 1 unit
Show your work:
Perimeter =
units
Perimeter Patrol — Page 2
Name: ________________________
3
The perimeter of the trapezoid-shaped garden is 28 feet. Three of the side lengths are shown. What is the length of the missing side?
8 ft 5 ft 5 ft ? ft
Show your work:
Missing side =
feet
4
Liam is putting a ribbon border around a rectangular picture frame. The frame is 9 inches long and 6 inches wide. How many inches of ribbon does Liam need to go all the way around the frame?
9 inches 6 in.
A 15 inches
B 24 inches
C 30 inches
D 54 inches
5
Which two rectangles below have a perimeter of 20 centimeters? Circle the two correct letters.
A
6 cm 4 cm
B
10 cm 2 cm
C
8 cm 2 cm
D
7 cm 4 cm
Show your work:
Perimeter Patrol Answer Key
Perimeter Patrol — Answer Key
Grade 3 Math • ILEARN Practice Review • Teacher Guide
5 Questions • Standard 3.M.7
1 Polygon Perimeter (Multiple Choice)
Answer: C (30 centimeters)
Solution: Add all five side lengths of the pentagon: \(6 + 6 + 5 + 5 + 8 = 30\text{ cm}\).
ILEARN Tip: Watch out for students who only add two or four sides (distractor A: 19 cm omits two sides; B: 24 cm omits one 6 cm side).
2 Unit Grid Counting (Constructed Response)
Answer: 18 units
Solution: Count the unit segments around the outside of the L-shaped figure: \(2\text{ (top)} + 2\text{ (inner down)} + 3\text{ (inner across)} + 2\text{ (right)} + 5\text{ (bottom)} + 4\text{ (left)} = 18\text{ units}\).
ILEARN Tip: Remind students to count the outside edges, not the shaded squares inside (area = 10 square units). Tick-marking each edge as they count prevents skipping the inner corner!
3 Missing Side Length (Constructed Response)
Answer: 10 feet
Solution: First add the three known sides: \(8 + 5 + 5 = 18\text{ feet}\). Then subtract from the total perimeter: \(28 - 18 = 10\text{ feet}\).
ILEARN Tip: Students often stop after adding the three given sides (\(18\text{ ft}\)) instead of subtracting from the total perimeter. Encourage checking by adding all four sides: \(8 + 5 + 5 + 10 = 28\).
4 Rectangular Word Problem (Multiple Choice)
Answer: C (30 inches)
Solution: Opposite sides of a rectangle are equal, so the four sides are \(9, 6, 9,\) and \(6\) inches. Total ribbon: \(9 + 6 + 9 + 6 = 30\text{ inches}\).
ILEARN Tip: Classic distractors: A (15 in.) adds only the two labeled sides (\(9 + 6\)); D (54 in.) multiplies to find area (\(9 \times 6\)). Have students label the two blank sides first!
5 Compare Perimeters (Multi-Select — 2 Answers)
Answers: A and C
Solution: Calculate the perimeter for each rectangle: A: \(6 + 4 + 6 + 4 = \mathbf{20\text{ cm}}\) • B: \(10 + 2 + 10 + 2 = 24\text{ cm}\) • C: \(8 + 2 + 8 + 2 = \mathbf{20\text{ cm}}\) • D: \(7 + 4 + 7 + 4 = 22\text{ cm}\).
ILEARN Tip: Rectangle B (\(10 \times 2\)) has an area of 20 sq. cm—a classic trap for students who confuse area and perimeter.
Scoring Suggestion: 1 point each for Questions 1–4; 1 point for Question 5 (or 0.5 pt per correct letter A and C). Total: 5 points.
