## Tuesday, December 05, 2006

### Measuring Guilt

It is raining today. This is not an unusual occurrence for this time of year.

We all know that rainfall in England varies widely with the Lake District being the wettest part and parts of the south east receiving almost a third less rain. We can all recall fondly how to make a rain gauge.

Aim
To estimate the point at which a rain gauge becomes too small to accurately represent rain fall.

Apparatus
Two different plastic containers with different heights and diameters.
Waterproof marker
Plastic Ruler

Method
Put the rain gauges outside on a level surface, away from any overhanging eaves or trees. Leave the gauges outside all week.
Measure the rainfall every day at about the same time of day.

Results (Or Eleven Plus Question)
How much does the diameter of the container affect the amount of rain being gathered?
If we have a large diameter gauge we expect more rain drops to be caught. The wide base however will spread the rain over a greater area in the container.

A narrower diameter gauge will catch less rain - but the drops will be at an equivalent depth.

I wonder how many eleven plus questions this topic covers? At first glance it seems we are looking at circles, volume, area, graphs, comprehension, metric system, problem solving - the list just goes on and on. We all know that we are more likely to retain information if we have thought about and discussed it.

Of course you do not have to do this experiment practically. We all remember: Rain, rain go away, come again another day. But if your child had needed just one more mark to pass - would you not feel guilty for ever?