Perimeter Patrol Slides Math Detective Academy
Perimeter Patrol
Let's become boundary detectives! We will learn how to measure the outside edge of any shape using colors, grids, and hands-on tools.
Lesson 1: The Outer Edge
Slide 1 of 8
Vocabulary Patrol
What is Perimeter?
The perimeter is the total distance around the outside of a shape.
Think of it like a fence around a yard, or a collar around a puppy!
Inside
The Red Line is the Perimeter!
Trace the outside with your finger! Slide 2 of 8
Hands-On Practice
Pipe Cleaner
Geoboard
Use physical pipe cleaners, yarn, or rubber bands to build boundaries!
Let's Build It!
1
Take a **pipe cleaner** or **piece of yarn**.
2
Wrap it tightly around the **exact outside edge** of a block or card.
3
Stretch that helper string out in a straight line to see **how long** the total perimeter is!
Teacher Tip: Keep manipulatives ready at desks. Slide 3 of 8
Method 1: Grid Counting
1
2
3
4
12
5
11
10
9
6
4 units
3 units
Count every single outer grid unit!
Count the Steps!
When a shape is on a grid, you can find the perimeter by counting the **outside edges** like steps.
Tap and count each unit path aloud as you walk all the way around!
Count around: 1, 2, 3, 4, 5, 6, 7, 8... Slide 4 of 8
Method 2: Color-Coded Sides
My Desk
Red Side = 4 Orange Side = 4 Blue Side = 3 Green Side = 3
Color Match!
Match the **colors** of the sides to your addition equation!
We use colors so we never forget a side or count it twice. Every side gets its own color helper!
Each side is a different road to travel! Slide 5 of 8
Perimeter Math
Add All the Sides Together!
4
Red
3
Blue
4
Orange
3
Green
=
14
Total
Start at the top red side and add going clockwise so you do not miss any side!
4 + 3 = 7. Then 7 + 4 = 11. Then 11 + 3 = 14! Slide 6 of 8
Guided Challenge
Top Side = 2 Bottom Side = 2 Left = 2 Right = 2 Square
Let's Try One Together!
This shape is a square! All four sides are 2 inches long.
What is the Perimeter?
2 + 2 + 2 + 2 = ?
Hint: Count by twos! 2, 4, 6, ... Slide 7 of 8
MISSION ACCOMPLISHED
You Are Perimeter Patrol Officers!
Great job! You measured boundaries, counted outer edges, and added side lengths like real math detectives!
Ready for the Activity Sheets! Slide 8 of 8
Perimeter Patrol Worksheet Perimeter Patrol Practice
Grid Counting Mission
LEVEL 1: GRIDS
Officer Name:
Date:
How to Solve:
Count each single square edge on the outside border of the shape. Write the number in the path as you count around. Then write your total answer below!
SHAPE A
Count the outer units:
Tap and count each outside block edge.
My Answer:
Perimeter =
units
1
2
3
8
4
7
6
5
SHAPE B
Count the outer units:
Trace your pencil around to count.
My Answer:
Perimeter =
units
1
2
3
4
10
9
8
5
Page 1 of 3 • Let's stay on patrol!
Perimeter Patrol Practice
Color Match Addition
LEVEL 2: COLOR ADD
Officer: ________________________ Date: ________________
How to Solve:
Look at the color of each side. Write that number in the matching color-coded box below. Add the numbers together to find the perimeter!
SHAPE C Rectangle
Red = 5 Orange = 5 Blue = 2 Green = 2
Write numbers in color boxes:
=
SHAPE D Triangle
Blue = 4 Green = 4 Red = 3
Write numbers in color boxes:
=
Page 2 of 3 • Excellent work, Officer! Keep going!
Perimeter Patrol Practice
Independent Patrol
LEVEL 3: CHALLENGE
Officer: ________________________ Date: ________________
How to Solve:
Let's try some on your own! Add the numbers on all sides of the shape together to find the total perimeter. Write your steps.
SHAPE E Perfect Square
SQUARE 3 in 3 in 3 in 3 in
Write your addition:
=
SHAPE F Tall Box
RECTANGLE 2 in 2 in 4 in 4 in
Write your addition:
=
Perimeter Patrol Teacher Guide Teacher Facilitation Resource
Perimeter Patrol Guide
FOR INSTRUCTORS ONLY
Key Learning Objectives
Identify perimeter as the outside boundary of 2D shapes.
Find perimeter by counting individual grid segments.
Use color cues to successfully select and add side lengths.
Tactile Manipulatives Prep
Yarn / Pipe Cleaners: Pre-cut pieces to match the boundary outlines of standard block squares.Geoboards: Put rubber bands around shapes, and let students physically count the outer pegs.
Facilitation Sequence
SLIDES 1-3
Introduce & Connect To Physical Boundaries
Discuss what boundaries exist around us (fences, desk edges). Have students hold a block and trace its outer rim with their finger. Explain that this path length is the perimeter .
SLIDE 4
Grid Counting & Edge Scanning
Emphasize counting only the lines touching the outside air . A common error is counting the interior grid squares themselves instead of the outer boundary edges.
SLIDES 5-7
Color-Coded Matching Scaffold
Demonstrate how each color (Red, Blue, Green, Orange) has a matching number. Have students match colored crayons to the corresponding sides on Page 2 of the worksheet.
Common Misconceptions
Misconception: Area Confusion
Students count the whole interior boxes instead of outer segments.
✔ Fix: Block shape interiors with cards so only borders show.
Misconception: Corner Double-Counts
Students get stuck on corners and count one corner segment twice.
✔ Fix: Use a physical starting peg to block double-counts.
Worksheet Answer Key (Problems 1 - 6)
Problem 1 (Shape A) 8 units
Problem 2 (Shape B) 10 units
Problem 3 (Shape C) 14 units (5 + 2 + 5 + 2)
Problem 4 (Shape D) 11 units (4 + 4 + 3)
Problem 5 (Shape E) 12 inches (3 + 3 + 3 + 3)
Problem 6 (Shape F) 12 inches (4 + 2 + 4 + 2)
Perimeter Patrol Series • Educational Design Resources • 2026
