Teacher background

Source: http://www.scootle.edu.au/ec/viewing/S7154/Heating-up-2013/teacher_bg_info.html

Heat is a form of energy created by the movement of molecules in an object. All matter is made up of atoms and molecules (groupings of atoms). The atoms and molecules of a material are always moving. Even objects which are very cold have some heat energy because their atoms and molecules are still moving.

When molecules get more energy in them than they had before, they move faster, and we call that heat. Things are hot if their molecules are moving quickly and cold if their molecules are moving more slowly. Temperature is a way of measuring how fast the molecules are moving.

Heat itself isn’t a ‘thing’ but rather a process of energy transfer. For example, when you hold a cup of hot coffee, heat flows from the cup to your hand—the hot thing warms up a cooler thing by the transfer of heat or heat energy. As the cup of coffee is hotter than your hand, the molecules in your hand move faster as heat energy flows from the cup to your hand. Over time, the molecules of the hotter object slow down and the molecules of the colder object speed up until eventually the two objects are the same temperature.

If you leave your cup of coffee on your desk and come back to it later, the heat will have flowed from the cup to the room until the coffee is the same temperature as the room (called equilibrium).

Heat has its origins in other forms of energy:

• The Sun changes nuclear energy into light and heat energy.
• A fire and living cells can change chemical energy into heat energy.
• Some electrical devices can change electrical energy into heat energy.
• Kinetic (motion) energy can be changed into heat energy through friction.

These are all examples of primary sources of heat. We might produce heat as a side product of any work we might do.

Secondary sources of heat do not produce heat themselves but are previously heated by a primary heat source. If then moved to a cold environment they exchange heat with objects around them until all materials reach the same temperature. Students’ conceptions

Taking account of students’ existing ideas is important in planning effective teaching approaches which help students learn science. Students develop their own ideas during their experiences in everyday life and might hold more than one idea about an event or phenomenon.

Students might think that the terms ‘hot’ and ‘cold’ are absolutes and opposites. However, ‘hot’ can be translated as ‘has a higher temperature than me’ and ‘cold’ as ‘has a lower temperature than me’. We intuitively understand the world in terms of what is hot or cold to us, but this would be very different if, for example, we had an internal body temperature of 120°C.

Students might think that ‘cold’ moves from one material to another. Statements such as ‘Don’t let the cold in!’ imply this. Heat energy always transfers from the hotter object to the colder one.

Cool facts about heat. Beyond penguins and polar bears:

• http://beyondpenguins.ehe.osu.edu/issue/keeping-warm/cool-facts-about-heat

Cool cosmos ‘What is heat?’

• http://coolcosmos.ipac.caltech.edu/cosmic_classroom/light_lessons/thermal/heat.html [Opens new Window]
• Burgoon, J., Heddle, M. & Duran, E. (2010). ‘Re-Examining the Similarities Between Teacher and Students Conceptions About Physical Science’, Journal Science Teacher Education (2911), 22:101–114.
• Hapkiewicz, A. (1992). ‘Finding a List of Science Misconceptions’, MSTA Newsletter, 38 (Winter ’92), pp. 11–14.
• Skamp, K. (Ed.). (2012). Teaching Primary Science Constructively (4th Edn). South Melbourne:

Cengage Learning Australia.

To access more in-depth science information in the form of text, diagrams and animations, refer to the PrimaryConnections Science Background Resource which has now been loaded on the PrimaryConnections website: www.primaryconnections.org.au [Opens new Window].

Note: This background information is intended for the teacher only.