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NEW online articles for Primary
Science "If you can't stand the heat..." | ||
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Energy & Forces Level D |
Learning activities e.g. |
Additional advice from Guide for Teachers & Managers |
| EF-D1.1 |
Click for Target Menu |
Properties &
uses of energy |
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distinguish between 'heat' and 'temperature' |
measure the temperature of
warm water in a mug and at intervals as it cools, keeping clear records
of findings.
give an explanation of the drop
in temperature, referring to the heat energy that is being lost. monitor and record
the temperature, in a range of places over 24 hours, using a
temperature sensor |
Avoid using hot water and mercury thermometers. Use a digital thermometer for safety. Temperature tells us how hot an object is; this is usually measured in degrees Celsius (ºC). However, this measure does not tell us how much heat energy the mug contains. A mug of water at 45 ºC has a temperature of 45ºC and a certain amount of energy. If we add a second mug of water at 45ºC the temperature remains the same but we have doubled the amount of heat energy. |
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Introduction
In the 5-14 guidelines (see above) is a seemingly innocent, little, Knowledge and Understanding requirement ( aka target ) : Distinguish between heat and temperature (Energy and Forces. Properties and uses of energy. Level D).
Easy, peasy? Far from it, given that the pupils will come to this topic with all
sorts of mental models of their own about heat and cold. Here we suggest a
number of useful questions and some investigative work which should assist to
challenge children’s preconceptions and help develop further understanding of
what can be a tricky, and fairly abstract concept. As usual we’ve thrown in odd
historical, technological and geographical references. This is in continuation
of our vain, cross-curricular, quest for a ‘joined-up’ approach to science.
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What
difference to our senses is there from a freshly made cup of hot chocolate and a
chocolate ice-cream? Both taste much the same. One feels hot and the other feels
cold. Are our senses determining the same thing and might that ‘thing’ be
“heat”? Does ice-cream contains less heat than cocoa? In cold weather when we
wrap ourselves in ‘warm’ clothing, is this to keep cold out or keep heat in? It
would seem from observation that heat flows from a hot object to its cooler
surroundings. Temperature is a measure of how hot an object is. For such
measurement we can use a thermometer.
Around
the end of the 16th century, both Gallileo (left) and Sactorious investigated
methods of measuring heat in air or liquids, both arriving at designs not unlike
those of thermometers we use today, with a glass bulb and tube filled with water
or alcohol. Early thermometers made an arbitrary measure of heat, the lowest
mark on the scale would be the coldest day in winter and the highest mark the
hottest day in summer. This meant that a thermometer made and marked in a town
in Italy would not read the same degree of ‘hotness’ as one made in a town in
Scotland.
It
was left to Daniel Fahrenheit, a thermometer maker, to design an instrument that
could be used anywhere in the world. Between 1707 and 1714, he developed designs
for an alcohol-filled thermometer, with a scale based on three points. Zero was
freezing point of a salt/water mixture, 32° was the
freezing point of water, and 96° body temperature (close
but not quite right). In 1714 he did what no one had done before, he made a pair
of thermometers that both gave the same readings. This was a great achievement,
of help to early chemists and wine producers. This made for lots of cheery
alchemists. Later Fahrenheit made mercury thermometers where he used the boiling
point of water instead of human body temperature, a less arbitrary fixed point.
A
few years later Anders Celsius introduced the Centigrade scale where the melting
point of ice was 0° and the boiling point of water 100°.
This is the scale we use today, but it is now named ‘Celsius’ after the
inventor.
