A blog about teaching and learning in a maths classroom.

Perimeter of curved shapes

Saturday, 08 August 2009 | 1 Comment

This week, Year 9 were looking at finding the perimeter of shapes that include curves (parts of a circle).

Along the way, I remembered I had this photo of a playground in my local area.

Click image for a larger version

Here it is in Google Maps (sorry, no link to the actual site):

From my notes when I took the photo, the radius of the circle is 11.75m.

How could you use this?

  • I used it as a review the day after we had worked out how to calculate the perimeter of part of a circle. The scenario set was “how does the builder plan for the number of bricks required?”
  • If I had remembered I had the image before we did the lesson, I would have used it as an introduction – “how are you going to solve this problem?”

Having only got a projector in my classroom this year, this is the sort of stuff I’ve been wanting to do since I started teaching.

Feel free to take this image and use in your own classroom. Obviously for a more senior/advanced class you could calculate other things like the length of an arc formed by the two seats.

Photo - Curved Wall ZIP, 736 KB
This work is licensed under a Creative Commons License (?).

Posted in • Lesson IdeaCirclesMediaPhotoTechnologyProjector ResourceWhat can you do with this? | Short URL:


Kate Nowak on  10 August 09  at  02:33 AM #
Great use of photo + google maps! It can be hard to find circle applications. Thanks for sharing. I think throwing it on the screen as an unfamiliar problem is a good instinct.

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Simon Job — eleventh year of teaching maths in a public high school in Western Sydney, Australia.
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