MathsClass

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.

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