The note
How schools teach it now
Split the shape into rectangles (or take a small rectangle away from a big one), find each area, then add or subtract. Missing sides come from the sides you already know.
5-minute kitchen-table activity
Sketch a room in your home as an L-shape with real measurements. Your child splits it into rectangles to work out how much carpet you'd need.
Worked example
An L-shape is a 10 cm by 8 cm rectangle with a 4 cm by 3 cm rectangle cut from one corner. What is its area?
- Whole rectangle: 10 × 8 = 80 cm².
- Cut-out piece: 4 × 3 = 12 cm².
- 80 − 12 = 68.
Answer: 68 cm²
Common mistakes to watch for
- Counting the overlap twice when splitting the shape.
- Missing a side when adding up the perimeter.
- Thinking a corner cut-out makes the perimeter smaller (for an L-shape it stays the same).
Encouragement
- Try saying
- “Can we cut it into rectangles we know?”
- Rather than
- “This one's too tricky, skip it.”