Mathematics · Foundation

Active learning ideas

Using Informal Units to Measure Length

Active learning works because young children develop spatial reasoning best through physical movement and hands-on materials. Handling objects like blocks or paperclips lets students feel the direct relationship between unit size and count, turning abstract ideas into tangible understanding.

• ACARA Content Descriptions
• AC9M6M01

• 20–40 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Experiential Learning
• 25 min · Pairs

Partner Chain: Measuring Books

Pairs select classroom books and measure perimeter using linking cubes laid end-to-end. They count units for each side, add totals, then switch units like hands for comparison. Record findings on charts and discuss differences.

How many blocks long is this book?

Facilitation Tip

During Partner Chain: Measuring Books, circulate and gently nudge pairs to slide blocks together so they touch but do not overlap.

What to look for

Provide students with a pencil and a set of 10 identical blocks. Ask them to measure the length of their desk using the blocks. Observe if they place the blocks end-to-end without gaps or overlaps and ask: 'How many blocks long is your desk?'

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

Activity 02

• Experiential Learning
• 35 min · Small Groups

Shape Hunt: Perimeter Paths

In small groups, students find polygons like windows or drawings, trace outlines on paper, and cover with straws or fingers. Count units per side and total perimeter. Share results, noting irregular shapes.

Can you measure the table using your hands?

Facilitation Tip

For Shape Hunt: Perimeter Paths, demonstrate how to trace the outline first with a finger before placing paperclips along the edge.

What to look for

Give students a drawing of a simple rectangle and a strip of paper. Ask them to trace the perimeter of the rectangle with the paper strip and then cut the strip to match the perimeter. Finally, ask them to count how many paper strips long the perimeter is.

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

Activity 03

• Experiential Learning
• 40 min · Whole Class

Unit Swap Challenge: Whole Class

Display a long rope; class measures perimeter using blocks first, records count, then repeats with larger units like feet. Tally results on board and graph comparisons to spot patterns.

Why might we get a different answer if we use different-sized objects to measure?

Facilitation Tip

In Unit Swap Challenge, pause the class after the first round to ask which unit felt easier to use and why.

What to look for

Ask students: 'Imagine you measured your book using large blocks, and your friend measured the same book using small buttons. Whose measurement would have more items? Why?' Listen for explanations about the size of the unit affecting the count.

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

Activity 04

• Experiential Learning
• 20 min · Individual

Build and Measure: Individual Mats

Each student builds irregular polygons with toothpicks on mats, then measures perimeter using beads. Adjust for full coverage, recount, and label drawings with unit counts.

How many blocks long is this book?

Facilitation Tip

During Build and Measure: Individual Mats, provide small sticky notes so students can mark where each unit ends, keeping their place as they iterate.

What to look for

Provide students with a pencil and a set of 10 identical blocks. Ask them to measure the length of their desk using the blocks. Observe if they place the blocks end-to-end without gaps or overlaps and ask: 'How many blocks long is your desk?'

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

A few notes on teaching this unit

Teach this topic by letting students experience measurement mistakes first. Use clear, short language like ‘touch to edge, no gaps, no overlaps’ instead of abstract rules. Research shows children refine their understanding when they notice inconsistencies themselves, so plan time for them to compare their counts with classmates after each measurement.

By the end of these activities, students will line up units without gaps or overlaps, explain why unit size affects the total count, and measure perimeters of simple polygons using informal units. They will compare measurements with peers and adjust their techniques based on feedback.

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Watch Out for These Misconceptions

• During Unit Swap Challenge, watch for students who assume the larger block will always give a smaller count because it feels heavier or takes more space in their hand.

  After the first round, ask each group to display their measurements side by side so students see that fewer large blocks fit along the same edge compared to small ones, prompting them to verbalize the inverse relationship.

• During Partner Chain: Measuring Books, watch for overlaps or visible gaps between blocks.

  Have students remove the blocks and look at the pencil marks left behind, then re-place the blocks with the teacher modeling how to slide each one snugly against the next without pushing over the edge.

• During Shape Hunt: Perimeter Paths, watch for students who include the inside of the shape or skip edges entirely.

  Ask students to trace the edge with one finger while counting aloud, emphasizing ‘around the outside only,’ and have partners verify by holding the paperclips along the traced line.

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Methods used in this brief

• Experiential Learning