What happens when it not only rains but it pours. 

26 03 2017

My brother lives on a farm in central NSW. Tuesday morning they had over 100 mm of rain in the order of 4 hours. Wednesday afternoon there was a further 63 mm in half an hour and Thursday afternoon it started raining heavily about 5. By about half an hour later there’d been just under another 50 mm.

Some of the water from the local to distant area runs past their house and into a creek.

When the last fall of rain came the water running past the house was about 20 m across and 400 mm deep and running at about 40m/min. My brother watched a moving leaf to get the rate of flow. As the runoff from the rain increased, the depth of the water increased to about 700 mm.

If calculations are made on 40 m/min X 20 m X 400 mm, you get 320 cubic metres per minute which is 19200 cubic metres per hour which is 19200000 litres per hour or 19.2 megalitres per hour.

It has been running at least this deep for the last 48 hours which calculates to be 921.6 megalitres or 921600 cubic metres of water.

At the times where the depth raised to 700 mm the rate of flow would have been faster- it was dark so we can only estimate that it was possibly at least half as fast again. This calculates to 50.4 megalitres per hour or 50400 cubic metres of water per hour.


That 3 day rainfall is half the average annual rainfall.

All in the day of being a farmer!





Imaginary Oil Spill Mathematics Lesson by Nanci Hutson

3 02 2017

Here’s an idea connecting Measurement to its applications in the adult world. 





Measuring Without any Instruments

12 03 2014

Today in Year 9 we gave the classes the scenario where a helicopter needed one hectare to safely land to pick up an injured bush walker. How could they estimate the area?
We took them our to the oval and lined them up along one side. They all walked out what they thought was 10m. We came behind with a trundle wheel and showed them 10m. They lined up along this 10m Mark and counted their steps back to the starting line.
They then lined up on the perpendicular side having practiced stepping a metre using a metre rule. They again stepped out 10m using 1 m steps. We again used the trundle wheel to show 10m. This time they lined up and counted their running steps back to the start.
They were to to remember both measurements and to compare the difference.
They were told that normal walking steps is the more accurate stepping method over a distance.
They were also told that farmers regularly use this stepping method to estimate when they will finish a paddock so family members can return to assist them in moving into a new paddock with large machinery.

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Lots of Mathematics Here

20 12 2013

Today I visited Tian Tan Buddha or Big Buddha which is 23m high itself or almost 34m high including the podium. It is 202 tonnes of bronze, which you reach after climbing 268 steps following a short walk from the terminus of the 5.7km Ngong Ping 360 cable car taking 25 minutes from Tung Chung.

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