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Math activity

Perimeter Patrol

Walk around the edges of things! Count your steps as you walk around a rug, a table, or a room. Discover that the 'walk around' is called the perimeter.

MovementAbout 20 minutesScreen-freeParent help expected

Materials and setup

How this changes by age

Pre-K (ages 3–4)

Walk around the edges of things! Count your steps as you walk around a rug, a table, or a room. Discover that the 'walk around' is called the perimeter.

Difficulty 1 of 3

Steps

  1. Stand at one corner of a rug or mat. Walk around the edge, counting each step.
  2. How many steps did it take to walk all the way around?
  3. Now walk around the kitchen table, counting steps. Is it more or fewer steps than the rug?
  4. Try walking around 3 different objects. Which one took the most steps?
  5. Explain: 'The distance all the way around something is called the perimeter!'
  6. Tell a grown-up one thing that surprised you.

Learning objectives

  • Understand perimeter as the distance around an object
  • Measure perimeter using non-standard units (steps)
  • Compare perimeters of different objects

Kindergarten (ages 5–6)

Measure the perimeter of flat objects by placing a string around them and measuring the string. Compare perimeters of different shapes.

Difficulty 2 of 3

Steps

  1. Gather string, a ruler, and 5 flat objects (book, placemat, picture frame, piece of paper, cutting board).
  2. Wrap string around the edge of each object. Cut or mark the string where it meets.
  3. Lay the string flat and measure it with a ruler. That length is the perimeter!
  4. Record all 5 perimeters in a list from shortest to longest.
  5. Draw 3 shapes on paper, measure each side with a ruler, and add all sides to find the perimeter.
  6. Tell a grown-up one thing that surprised you.

Learning objectives

  • Measure perimeter using string and a ruler
  • Understand perimeter as the sum of all side lengths
  • Compare and order perimeters of different objects

Early elementary (ages 6–8)

Calculate perimeters of rooms, objects, and drawn shapes by measuring sides and adding. Explore the relationship between perimeter and side lengths for rectangles.

Difficulty 2 of 3

Steps

  1. Use a tape measure to find the perimeter of 3 rooms in your house. Measure each wall and add them up.
  2. Draw 5 different rectangles on graph paper. Calculate each perimeter using P = 2(length + width).
  3. Challenge: can two different rectangles have the SAME perimeter? Draw 3 different rectangles that all have a perimeter of 24 units.
  4. Measure the perimeter of 5 objects (a book, a phone, a window, a picture frame, a door).
  5. Solve 4 word problems: 'A garden is 12 feet long and 8 feet wide. How much fencing do you need?'
  6. Design a room with a specific perimeter of 40 feet. Draw it on graph paper and label all sides.
  7. In one sentence, tell a parent or sibling what surprised you today.

Learning objectives

  • Calculate perimeter by measuring and adding all side lengths
  • Use the perimeter formula for rectangles: P = 2(l + w)
  • Solve real-world perimeter problems involving fencing, framing, and borders

Upper elementary (ages 8–10)

Calculate perimeters of complex and irregular shapes. Solve problems involving perimeter with missing side lengths, and optimize perimeter for given area constraints.

Difficulty 3 of 3

Steps

  1. Calculate the perimeter of 5 irregular polygons where you must first find missing side lengths using the given dimensions.
  2. Measure the perimeter of your yard or a section of your neighborhood using a tape measure or by pacing.
  3. Investigation: for a fixed area of 36 square units, what rectangle shape gives the smallest perimeter? The largest? Try 1x36, 2x18, 3x12, 4x9, 6x6.
  4. Calculate the perimeter of 3 composite shapes (L-shapes, T-shapes) by identifying and measuring all outer edges.
  5. Real-world problem: if fencing costs $4.50 per foot, how much would it cost to fence your yard? A rectangular garden?
  6. Write a report comparing the relationship between area and perimeter. Include your data and a conclusion about which shape is most efficient.
  7. In one sentence, tell a parent or sibling what surprised you today.

Learning objectives

  • Find missing side lengths in polygons and calculate total perimeter
  • Calculate perimeters of composite and irregular shapes
  • Analyze the relationship between perimeter and area for different rectangles

Safety and evidence note

Read the full activity before beginning. An adult should supervise tools, heat, food, outdoor work, movement, and experiments as appropriate. Completion records that the activity was done; the child’s explanation, work sample, photo, or demonstration is stronger evidence of learning than a completion check alone.

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