Lesson 1 of 9
The distance all the way around
Show on a big screenA family puts wire round its courtyard before Diwali. The courtyard is the open yard of their house. How much wire is needed?
Step 1 of 5
- A courtyard, 8 m by 5 m.
- Walk the top: 8 m.
- Walk the right side: 5 m.
- Walk the bottom: 8 m.
- Walk the left side: 5 m. Total = 26 m.
The rule
The family needs 26 m of wire.
The perimeter of a shape is the distance around its edge. Walk every side once and add the lengths.
Perimeter is a length, a distance. Use centimetres (cm) for small things and metres (m) for big ones.
8 m + 5 m + 8 m + 5 m = 26 m
The courtyard's perimeter is 26 m — never just "26". Write the unit, because 26 alone could mean cm or m. This works for any closed shape, not only a rectangle. A closed shape has no gap in its edge.
Slide the lab to walk the edge.
Loading lab…
Try the lab to finish this lesson.