## Friday, February 18, 2011

### The Temperature of the Eleven Plus

We were working on graphs yesterday – and one graph came up converting Celsius to Fahrenheit and back again. Our rather eccentric science teacher at school used to get quite emotional about an apparent misuse of terms. He used to refer to Celsius as Centigrade. We will all be able to remember from school that Centigrade was devised to divide the temperature between freezing and boiling points of water into one hundred equal parts. As a science teacher he liked the exactness and the formality of the experiment. He just did not like the new name `Celsius’.

We were also regaled with stories about Galileo who noticed that when alcohol was heated in a narrow glass tube it expanded and rose in proportion to the increase in temperature. As school children we were upset that we could `play’ with boiling water but were not allowed to use alcohol in experiments. Life can be very unfair when you are at school in a science lesson.

Fahrenheit was a physicist who developed the temperature scale for a mercury thermometer. He was going to fix the blood temperature of a healthy man at 12 – but needed a more accurate scale. Water froze at thirty two degrees and blood at ninety six. Later on `normal’ blood temperature was refined at 98.6 degrees.

It was only in 1948 that Centigrade was renamed Celsius after a Swede Anders Celsius. The books we used at school were old. Our science teacher was old. The act of conversion lives on today.

Your eleven plus child may need to know that to draw and interpret a conversion graph you need two values. It is unlikely that an eleven plus child will be expected to remember that 0 degrees Celsius = 32 degrees Fahrenheit and 100 degrees Celsius = 212 degrees Fahrenheit. What then could be a possible question interpreting a conversion graph?

Degrees Celsius – from 0 to 100 - would be on the `x’ axis.

Degrees Fahrenheit – from 0 to 220 – would be on the `y’.

A straight line graph could be plotted.

The eleven plus question could be:

Change 60 degrees Fahrenheit to Celsius.

A boy we are working with is aiming at a top eleven plus pass. He joined us with mathematics at Level 5B – so it was evident that his mathematics was strong enough to pass the eleven plus with very little intervention. He does, however, enjoy the challenge of demanding and interesting questions.

We just hope that when he reaches the grammar school he is actually allowed to heat and experiment with alcohol. The fact that we were denied this opportunity has rankled till today.