## Hula Hoops, String, Circles and pi

15 May

I was recently asked by a friend (OK, it was a tweet by the excellent @thought_weavers aimed at anyone at all ) for my thoughts on introducing circumference and area to a class of year 6 pupils.

I quite liked my reply so I thought I’d blog about it at is is nice and simple.

Ingredients

Hula hoops, Coins, String, Scissors, Cans of baked beans {or other}, Anything else of a circular nature. Cotton

Instructions

Place various circular objects around the room along with scissors and string/cotton.

Split pupils into small groups or pairs and position them at an object.

Ask them to show where the diameter of the circle they have is. Then ask them to cut the string into a piece equal to the diameter.

Ask the question – how many times does the string fit areound the circle.

Investigate. Hopefully they will discover that it fits round just over three times (3.14 to be more precise, 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679
8214808651328230664709384460955058223172535940812848111745028410270193852110555964462294895493038196
4428810975665933446128475648233786783165271201909145648566923460348610454326648213393607260249141273
724587006606315588174881520920962829254091715364367892590360011330530548820466521384146951941511609 to be even more precise). That’s it, they have discovered pi.

That’s it really. Chance for pupils to investigate pi and see what it is and where it comes from. There are loads of worksheets and things for working out circumference and area but you can always explore a bit too with some tape measures etc – there are genrally plenty of circles to be found.

For pupils who forget how to calculate you could let them watch this (It will annoy them but stick in their heads):

Or this rhyme:

Tweedle dum and tweedle dee
Round the circle pi times d
If the area’s to be declared
Then you need pi r squared

Hope you take the opportunity to use the investigation.

Stephen

Posted by on May 15, 2011 in Uncategorized

### 2 responses to “Hula Hoops, String, Circles and pi”

1. May 20, 2011 at 11:06 pm

Hi. Math Teachers at Play 38 is already up at

http://mathandmultimedia.com/2011/05/21/math-teachers-at-play-38/