Teachers


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Scholarly reading
Book - Inventing Temperature: Measurement and Scientific Progress (Oxford Studies in the Philosophy of Science) by Hasok Chang.

[|The Differentiation of Heat and Temperature: An Evaluation of the Effect of Microcomputer Teaching on Students' Misconceptions. Technical Report 87-5.by Marianne Wiser in 1986] Wiser skirts round the issue by focusing on the ways that her students grappled with these two concepts and nowhere gave a clear idea of the meanings of the two concepts, except in the sense of focusing on the difference in being extensive and intensive respectively. Wiser found that her learners could carry out calculations better after using a computer but did not have a better conceptual system. A fascimile of the original paper is at this site. [|Can the Study of Thermochemistry Facilitate Students’ Differentiation between Heat Energy and Temperature? Mansoor Niaz] Journal of Science Education and Technology [|Volume 15, Numbers 3-4 / October, 2006] concluded that freshmen (20 year old) students, after studying thermodynamics, could not make this distinction clearly, and notes that adolescents have this problem, too. In Making Sense of Secondary Science, Driver //et al// in 1994 report a range of children's ideas about heat and temperature. Many children think of heat as a fluid (Harris, Hewson & Hamlyn, Erickson, Clough & Driver). Watts & Gilbert interpreted their results in terms of different forms of heat, some of which were described as motion. Tiberghien reported that many adolescents fail to distinguish between heat and temperature (see below for how this continues to be a challenge for adults, too). Some studies (e.g. Driver & Russell in Malaysia and England) use examples of mixing water at different temperatures to explore children's ideas, and come up with multiple confusions about temperature. Appleton found that many Australian children did not know what a mercury-in-glass thermometer was, or what it was used for. He also discovered that they were not so good at estimating temperature. These studies seem to mirror the findings from history discussed below. Crosland M P (1978) //Gay-Lussac Scientist and Bourgeois// Cambridge University Press, Cambridge is a relatively cheap source of information about this famous scientist. Frängsmyr T, Heilbron J L & Rider R E (Eds) (1990) //The Quantifying Spirit in the 18th Century// University of California Press, Berkeley [|Biography of E H Weber, psychologist studying sensory stimuli, including temperature.] Weber created the 3 bowls experiment used in many early science courses to show that using the hand to ascertain temperature can be very misleading. [|MF Tritsch] updated this experiment in 1990.

Historical problem of distinguishing between heat and temperature
[|Differentiating heat and temperature]

Heat can be an elusive characteristic for many. Wikipedia gives a short history of attempts to pin down an explanation of what heat is ([|here)]. A common theme in these explanations is the idea of motion (e.g. [|Abū Rayhān Bīrūnī] (11th century), Abd Allah Baydawi (13th century), Avicenna (1253), Bacon (around 1600), Hooke (mid 17th century), Bernoulli (1738), Heat was seen as a fluid or substance for a long time (e.g. Becher, who created the phlogiston idea (17th century), Black (1761), Lavoisier with his caloric theory (1783), Carnot (1824), Clausius (1850)) The idea that heat is a fluid is still entrenched in some of the language we use, such as heat flow and heat capacity. The fluid protagonists did not entirely abandon the idea that heat is motion, since many associated fluid and motion. These ideas still abound today, especially in discussions with scientists becoming teachers who use explanations such as particles vibrating (despite also at the same time exhibiting close-packed touching in solids such as crystalline metals). See also for example in the Wikipedia link ([|here)] 'on a microscopic scale, conduction occurs as hot, rapidly moving or vibrating atoms and [|molecules] interact with neighboring atoms and molecules, transferring some of their energy (heat) to these neighboring atoms'. This explanation mixes the idea of hot (a macroscopic feature) with rapidly moving or vibrating atoms (a sub-microscopic feature) and such mis-matches are common, even among some professional scientists. Modern physics at undergraduate level side-steps the issue by involving algebraic functions for both macroscopic features of heat, and for the sub-microscopic explanations, e.g. in both classical and statistical thermodynamics. In these latter cases, concepts are subservient to mathematical treatments.

[|The Kelvin Library] gives access to selections from Kelvin's original library of papers.

Temperature is usually simplistically defined as a measure of hot and cold. 'Japanese has two words for "cold:" samui for coldness in the atmosphere or environment; tsumetai for things which are cold to touch', (from Online Etymology Dictionary, www.etymonline.com). However, 'hot' and 'cold' are difficult concepts to pin down, too. What we can say is that heat can move (as in a fluid?) from hot or cold, so these terms are closely linked with the direction of heat movement. The on-line dictionary, Wiktionary, states that cold means having a low temperature, while hot means having a high temperature, which makes the discussion tautological. Ma-Naim Chana and Bar Vada in Teaching thermodynamic using the particulate model of matter claims to be able to improve understanding by starting from the sub-microscopic level. However, their paper does confuse translational kinetic with vibrational kinetic energy. Nevertheless, they do acknowledge the need for understanding at the sub-microscopic level.

Such challenges to understanding should provide caution when we try to explain these terms to young, or even older, learners.

Zambrano provides an excellent discussion of the historical work on heat and temperature, and of classroom work (in Colombia) to construct a curriculum to improve teaching and learning.

[|Kelvin's Kids Club] at this web site has some activities to stimulate learning.

Uneven glass expansion giving rise to problems of temperature measurement
[|(here - Wikipedia)] This article reports how the uneven expansion and cooling of glass when the temperature changes provides an explanation for thermometers giving diffrent readings, even when properly calibrated. A thermometer heated to 100 Celsius and then cooled to 50 Celsius can give up to 0.7 degrees difference in readings when compared with one that has been cooled to 0 Celcius and them warmed to 50 Celcius.

Ideal temperature measurement and invention of Kelvin scale
[|Wiki - ideal temperature scale] An ideal gas is one whose change in volume (or pressure if the volume is fixed) is linear when temperature changes. This means that a volume of gas can be used to track changes in temperature, and even determine the temperature if calibrated. This thermometer is known as the Ideal Gas Thermometer. It might not be of much help, though, since an ideal gas does not exist! Help is at hand since some real gases behave as though they were ideal under usual atmospheric conditions. Hydrogen is one of these, especially at relatively low pressure.

To measure the temperature of an object, a hydrogen thermometer is placed in contact with the object, until the volume or pressure stops changing. Then the object is at the same temperature as the hydrogen thermometer, which can be found by measuring the gas volume or pressure under the same pressure as it was calibrated. Of course, the gas thermometer will have taken some heat energy from the object, and affected its temperature. Using the smallest possible gas thermometer will make this effect the smallest possible. In any case, we will know the object's temperature when the gas thermometer stops changing!

Other thermometers are calibrated against the gas thermometer, or via thermometers that have been ultimately calibrated using the gas thermometer. [|web site here] A site concerned with high quality calibration methods is [|here.] [|International Temperature Scale 1990 on the NPL site.]

[|Wikipedia explanation of heat] This article does try to explain that heat and thermal energy are not the same but in my view (John) fails abysmally. [|The physicsfront.org explains the difference between heat and temperature] This site uses a mixture of animations and experiments to explain the difference.