Mar 232017
We used strips of paper to measure the diameter and circumference of various circular/cylindrical objects.
We noticed that the circumference was:
- always bigger than the diameter
- about 3 times bigger
Mr Williams then made a spreadsheet of our results. Dividing the circumference of a circle by its diameter gives a special number called pi which is a never ending decimal that starts 3.141592…..
| Person | Iterm | Diameter (cm) | Circumference (cm) | Circumference/ Diameter | Pi | Accuracy |
| Lola | Paper roll | 4.2 | 13 | 3.095238095 | 3.141592654 | 0.04635455835 |
| Glue stick | 3.1 | 10.2 | 3.290322581 | 3.141592654 | 0.1487299271 | |
| Umbrella handle | 3.1 | 10.3 | 3.322580645 | 3.141592654 | 0.1809879916 | |
| Nailah | Whiteboard pen | 1.7 | 4 | 2.352941176 | 3.141592654 | 0.7886514771 |
| Mug | 8.5 | 26.7 | 3.141176471 | 3.141592654 | 0.0004161830016 | |
| Pipe | 1.9 | 6.5 | 3.421052632 | 3.141592654 | 0.279459978 | |
| Wilf | Whiteboard pen | 1.7 | 5.2 | 3.058823529 | 3.141592654 | 0.08276912418 |
| Hook | 0.5 | 2 | 4 | 3.141592654 | 0.8584073464 | |
| Whiteboard cleaner | 4.2 | 13.7 | 3.261904762 | 3.141592654 | 0.1203121083 | |
| Jake | Headphones | 3.4 | 12.1 | 3.558823529 | 3.141592654 | 0.4172308758 |
| Cork | 2 | 7.3 | 3.65 | 3.141592654 | 0.5084073464 | |
| Burger | 7.5 | 27 | 3.6 | 3.141592654 | 0.4584073464 | |
| Jiyan | Wipes | 7.2 | 26 | 3.611111111 | 3.141592654 | 0.4695184575 |
| Camera | 13.4 | 39 | 2.910447761 | 3.141592654 | 0.2311448924 | |
| Fire extinguisher | 11.2 | 35.3 | 3.151785714 | 3.141592654 | 0.0101930607 |
The spreadsheet shows how accurately we measured – Nailah was most accurate when measuring the mug!
We noticed that it was hardest to measure the smaller objects accurately.