Coffs Harbour Public School Blog

Courtesy & Honour – Principal:Leonie Buehler


iPad Circle Hunt Stage 3

Both class 5N and 5M set off this week on a maths quest to find the radius, diameter, circumference and area of selected circles. They used iPads loaded with QR readers to scan the QR codes Mrs Booth had created. These had the clues needed to find the next circles location. The students were paired and armed with a worksheet, ruler, pencil and iPad.  There were some sharp minds as area and circumference are Stage 4 (grade 7) outcomes and some students managed to complete some or all of this section. Well done 🙂 Everyone loved using the Star Walk and Solar Walk Apps to get the answers to the astronomy section of the activity. A big thank you to Mrs Bullen for loading all the apps onto the iPads and making them available for us.

Also a big thank you to Ms Jacka for supporting class 5M on Thursday.

Here are the tasks they were set:
Using a ruler, measure the radius of the various circles. Then use the formulas you have been shown to calculate the diameter, circumference and area of each circle. Don’t forget to label your units and add squared ² onto an area.  If you finish all of these go to your iPad and Star Walk App and ‘Sky Live’ to locate the names of the four planets rising . You need to find the radius, length of year (Earth years), and surface temperature (Celsius) of each planet.


  • Pi: π=3.14
  • Diameter:  d=2r (radius x 2)
  • Circumference: C=πd (diameter x 3.14)
  • Area: a =πr² (radius squared x 3.14)
An example would be: A circle has a radius of 6cm therefore 6 + 6 = 12cm, and the diameter is 12 cm. The circumference is then 12 x 3.14 (pi) = 37.68cm. Finally the area is calculated 6 x 6 = 36cm and 36cm x 3.14 (pi) = 113.04cm2 ( area always has a squared symbol).

The idea for this lesson came from a great teacher in America called Mr Avery and the link to his excellent class blog is in the blogroll. Here is the link to his blog post about The great Circle Hunt of 2012.

Mrs Booth

Do you use iPads for maths?



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