Mathematics · Grade 2

Active learning ideas

Perimeter: Measuring Around Shapes

Active learning works for perimeter because young students need to physically measure edges to grasp that perimeter is the total length around a shape, not just a single side or interior space. Moving and manipulating materials like yarn, straws, and paper clips helps students internalize the concept through touch and movement, making abstract ideas concrete.

• Ontario Curriculum Expectations
• Ontario Curriculum: Mathematics Grade 2, E2. Measurement: E2.1 choose and use non-standard and standard units of the same size to measure the side lengths of a polygon
• Ontario Curriculum: Mathematics Grade 2, E2. Measurement: E2.1 explain the properties of a polygon that make it possible to measure its perimeter

• 30–45 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Experiential Learning
• 30 min · Pairs

Hands-On: Yarn Perimeter Hunt

Provide yarn pieces for students to wrap around classroom objects like books or desks. They straighten the yarn and measure its length with rulers or cubes, then record the perimeter. Partners compare findings and discuss shape differences.

Differentiate between area and perimeter.

Facilitation Tip

During Yarn Perimeter Hunt, model how to wrap yarn tightly around the shape without overlapping or leaving gaps to ensure accurate perimeter measurement.

What to look for

Provide students with several simple polygons drawn on grid paper. Ask them to measure the sides using linking cubes and write the perimeter for each shape. Check their addition for accuracy.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 02

• Experiential Learning
• 45 min · Small Groups

Design: Garden Fence Challenge

On grid paper, students sketch rectangles with a 20-unit perimeter, labeling side lengths. They add the sides to verify and adjust if needed. Groups present one design, explaining their measurements.

Design a fence for a rectangular garden with a perimeter of 20 units.

Facilitation Tip

For Garden Fence Challenge, circulate to ask students to explain why their fence design matches the 20-unit perimeter requirement before they finalize it.

What to look for

Pose the question: 'If you have a rectangle with sides 5 units and 3 units, and another rectangle with sides 6 units and 2 units, which one has a larger perimeter? How do you know?' Listen for students correctly calculating and comparing the perimeters.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 03

• Experiential Learning
• 35 min · Pairs

Build: Straw Polygon Perimeters

Students connect drinking straws of fixed lengths to form triangles and rectangles. They measure and add side lengths for each shape's perimeter. In pairs, they create shapes with matching perimeters but different areas.

Justify why measuring all sides is necessary to find the perimeter.

Facilitation Tip

At Straw Polygon Perimeters station, remind students to record the length of each side before adding them up to avoid skipping measurements.

What to look for

Give students a drawing of a simple house outline. Ask them to measure all sides and calculate the total perimeter. Then, ask them to draw a different shape that has the same perimeter and label its side lengths.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 04

• Stations Rotation
• 40 min · Small Groups

Stations Rotation: Perimeter Stations

Set up stations: measure block structures, trace and measure student-drawn shapes, calculate fence perimeters on grids, and sort shapes by perimeter size. Groups rotate every 10 minutes, recording data.

Differentiate between area and perimeter.

What to look for

Provide students with several simple polygons drawn on grid paper. Ask them to measure the sides using linking cubes and write the perimeter for each shape. Check their addition for accuracy.

• Remember
• Understand
• Apply
• Analyze
• Self-Management
• Relationship Skills

A few notes on teaching this unit

Teach perimeter by starting with non-standard units to focus on the concept of total distance around, then transition to standard rulers. Avoid teaching formulas too early; instead, let students discover that adding side lengths gives the perimeter. Research shows that students who physically measure shapes develop stronger spatial reasoning and fewer misconceptions about measurement.

Successful learning looks like students using tools to measure all sides of shapes accurately, discussing why every side counts, and applying addition to find total perimeters. Students should also explain how perimeter differs from area and justify their measurements with evidence from hands-on activities.

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Watch Out for These Misconceptions

• During Straw Polygon Perimeters, watch for students assuming perimeter is the same as area.

  Have students cover the inside of their shapes with tiles to measure area, then compare it to the yarn-wrapped perimeter, discussing how the two measurements describe different things.

• During Garden Fence Challenge, watch for students measuring only the longest side of the rectangle.

  Prompt students to measure and label each side of their garden design with linking cubes, then ask them to explain why skipping sides would give an incorrect total perimeter.

• During Yarn Perimeter Hunt, watch for students thinking irregular shapes have no perimeter.

  Ask students to trace and measure classroom items with curved edges, like a wastebasket or a student’s handprint, demonstrating that all closed shapes have a perimeter.

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Methods used in this brief

• Experiential Learning
• Stations Rotation