This is taken from my Science Education textbook, The Art of Teaching Science. Is this a science lesson gone wrong? or a science lesson gone right?
Jim (not his real name) was explaining homeostasis to his Year 12 biology class. Homeostasis is the process where bodily inputs and outputs are balanced to maintain a constant internal environment. To model body temperature regulation, Jim used a car engine’s cooling system to show how heat input and output are balanced. The burning fuel produces plenty of waste heat and just the right amount of heat is lost through the radiator to keep the engine at its optimum working temperature without overheating (which will damage the engine). When we exercise, our muscles produce excess heat. In summer some of this heat is lost through the skin to stop the body from overheating (which will damage muscles and organs). In winter we add an insulating layers to reduce heat loss, again ensuring optimum temperature and maximum efficiency.
Jim assumed that his students were familiar with the way water flows in a circuit from the car engine to the radiator through the thermostat. Heat is lost from the engine to the air in the radiator. The thermostat controls the rate of heat loss and represents the temperature control in the thalamus. When we talked to the students at the end of the lesson, however, they said they had learned lots about car engines and cooling systems from the way the human body worked. The students understood the target better than the analogy.
The above excerpt is © Grady Venville and Vaille Dawson 2004, and not a party to this website’s standard Creative Commons license. It is used as fair use (properly attributed excerpt that should not effect commercial viability).
Reference: Harrison, A. (2004). Teaching and learning science with analogies. In G. Venville & V. Dawson (eds.), The Art of Teaching Science (p. 168). Crows Nest, NSW: Allen & Unwin. ISBN 978-1-74114-217-4