Fence Walk
Perimeter is the total length around a closed boundary. Add every outside side once. The inside space is a different measurement.
Before you try
Before you play, make a prediction: Perimeter measures… Explain what you expect and what part of the model will help you check it.
Try it out
Interactive activity
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What happened?
Move a control to see what changes and why.
The game practises one idea at a time with simple drawn pictures. Check the same idea with real objects and your NCERT textbook (Chapter 6: Measuring Length, pages 80–94).
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Try these ideas
- Trace the boundary and record the running length before choosing the total.
- Try a new puzzle with ↻. Describe what changed and which mathematical rule stayed the same.
- Complete a round, then explain your method before you move to the next one.
Why it works
Perimeter is the total length around a closed boundary. Add every outside side once. The inside space is a different measurement.
A 5 cm by 3 cm rectangle has perimeter 5 + 3 + 5 + 3 = 16 cm. Trace the boundary and record the running length before choosing the total.
Perimeter uses units of length. Do not confuse it with the area inside the fence.
This activity connects to Measuring Length, NCERT Class 4 maths, printed pages 80–94. Use the picture or objects to explain each step before relying on a calculation. The game practises one part of the chapter at a time; the other three activities extend the chapter’s ideas.
Worked example: Find the boundary length of a rectangle 8 m long and 5 m wide. The four sides measure 8, 5, 8 and 5 metres. Add all four: 8 + 5 + 8 + 5 = 26 m.
Check your understanding
Question 1 of 2
Perimeter measures…
A square has four sides of 3 m each. Its perimeter is…
Explain it in your own words
What changed? Why did it happen? Where might you notice this in everyday life?
For parents & teachers
- Try with everyday materials. Trace the boundary and record the running length before choosing the total. Ask the child to make a new example using paper, counters, household objects or a labelled sketch.
- Listen to the explanation. Perimeter uses units of length. Do not confuse it with the area inside the fence. Ask “How could we check?” and encourage a second representation of the same idea.