Measurement · Challenge 14 of 25 · about 6 min
Area and Perimeter of an L-Shape
Count tiles inside an L-shape and trace its outside boundary.
Year 4 challenge progress
0 of 25 complete
1 Read
Your challenge
An L-shape is made from unit squares at row 1 columns 1, 2 and 3, row 2 column 3, and row 3 column 3. What are the area and perimeter of the shape?
Take your time. Your answer is checked only when you choose Check Answer.
Curriculum details
- Curriculum code
- VC2M4M02
- Strand
- Measurement
- Focus
- Distinguish area from perimeter and measure both using units.
2–5 Notice · Build · Move · Connect
Interactive visual
An interactive Fill inside, walk outside model is ready. Choose Show Visual Trick to reveal and hear one mathematical change at a time.
Visual Trick
Fill inside, walk outside
Count the tiles for area and trace only the outside edges for perimeter.
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Step 1
Shade and count the five interior unit squares in Area mode.
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Step 2
Change to Perimeter mode and hide every shared edge.
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Step 3
Walk a line around the external boundary.
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Step 4
Count twelve outside unit edges.
6 Solve
Your answer
7 Check
Worked explanation
Why the answer makes sense
- Area counts the five filled unit squares, so the area is 5 square units.
- Five separate squares have 20 edges altogether, but four shared joins hide 8 edges.
- 20 − 8 = 12, so the perimeter is 12 units.
Challenge complete
This counts as one completed curriculum item. You can replay the model or review it again anytime.