New Perspectives in Science Education

This paper arises from the EU History and Philosophy in Science Teaching Project. Actions and results are the sole responsibility of the author.

Temperature was a rather elusive concept until it was measured in history. The development of instruments for quantitative measurement was vital for characterising the concept,  for explaining human sensations of hot and cold, for providing ways of exploring a range of temperatures greater than that of direct human experience, and for exploring the nature of the measuring instruments themselves.

Temperature is a basic concept in junior high school (lower secondary school) science. Through practical activities, it provides a tool for learners to start to distinguish between temperature and heat, largely through the effects on different phases of water at different temperatures. In many countries, including the UK, learners explore particle explanations for change in junior high school, and this activity is intended to build on that experience, and to consolidate it.

Traditionally, learners would be presented with traditional liquid-in-glass thermometers with very little idea of how it worked but an instrumental. The approach in this Case Study is to start from the construction of a particular thermometer, one of the first types in history, a gas thermometer. It is also important to give learners personal practical experience, so the choice here of equipment is made to ensure that most schools will have the relevant equipment. It differs from a more common approach based on expansion of liquids for more fundamental reasons. The first is that liquid expansion with increasing gas temperature is much more difficult using particle models to explain than increasing gas pressure. There are serious conflicts with the notion of liquid particles moving faster and their motion being curtailed by being in a condensed phase and this does not apply to a gas. Secondly, it is easy to experience increased pressure by its effect on the skin as a finger is placed over the end of the tube leading from the gas container.

The activity is relevant to lower secondary school science, and for all abilities.

In terms of history, gas pressure was easier to measure using relatively crude glass tubing since only height difference in a manometer is being measured. Liquid expansion requires much more uniform bore tubing, demonstrating the effect of precision glass making on temperature measurement.

Philosophical considerations include the impact of measurement in establishing scientific concepts, and ideas about standardisation, calibration and extending instrument limits of measurement.