What is actually going on inside a circuit? It’s impossible to see, and to explain it properly uses concepts way above primary school level. So how can we explain it? Time for a model!
Electricity is an abstract idea. We can see its effect on something like a light bulb, but it is very hard to understand what is happening inside a circuit.
To help understand what is going on, we need to use models or analogies. To use another frame of reference to help describe something. For example many people think about electricity in terms of something else – water flowing through pipes or traffic moving along roads. See Asoko (1995) Faulty Connections
Analogies as pedagogical tools each have their own strengths and limitations (Ramos 2011). But they have potential if they are properly used. Often one analogy won’t be enough. Chiu et al (2005) used two electrical analogies with one group of children and a single analogy to another group. Although each model had weaknesses, found that presenting children with several analogies aided their learning and understanding of how a circuit works.
Here are a few suggestions for models that could be used to help pupils begin to understand about electricity.
Water Pump
Imagine that the wires are pipes and filled with water. The pump is the battery. The pump switches on and pushes the water around the pipes. This is the flow of electricity, which we call current. The strength of the pump is the voltage – the bigger the push, the faster the water flows around the pipes and the bigger the current.
A water wheel represents a component such as a bulb. The faster the current, the faster the water wheel moves (the brighter the bulb)
String Loop
Use a small group of pupils and ask them to sit in a circle on the floor. Use a loop of string (or a hoop). Have them hold their hands out so that the string can pass between their thumb and forefinger. One child can then act as the battery, they start moving the string around in a circle. The string is the current, flowing around in a circuit. See this guide from the IOP for more detail (https://spark.iop.org/rope-loop-electric-circuit-model)
Sweetie Circle
The pupils stand in a circle with a plate of sweets at one end and a hoop at the other. The pupils walk around in a circle and as they pass the bowl they should take a sweet. When they reach the hoop they should eat the sweet and climb through the hoop (or do a star jump). They then return around the other side of the circle and back to the bowl.
In this model the pupils are the current and the plate of sweets is the battery. The sweets are the energy, which they use up in climbing through the hoop (the bulb) or doing the star jump.
Model railway
Ask the pupils to think about a model railway track set up as a simple loop. The train loads its goods at the station (the battery), delivers them to the factory (the bulb) and then returns to the station. In this model the tracks are the wires and the train is the current.
No model is perfect, they will usually fall down on some aspect of what actually happens inside a circuit. But the shortfalls could be discussed with the pupils. Pupils will need support in using any analogy to aid their understanding. The relationship between the parts of the model and what is being explained needs to be made explicit for them to make sense of the science behind the model (Ramos 2011).
For more analogies, see Asoko (1995) https://www.tes.com/news/faulty-connections
Teaching Approaches
The Institute of Physics has a pretty comprehensive guide to how to teach electrical loops. Check it out here.
References
Asoko, H., (2005) Faulty Connections : https://www.tes.com/news/faulty-connections
Chiu, Mei-Hung & Lin, Jing-Wen. (2005). Promoting fourth graders’ conceptual change of their understanding of electric current via multiple analogies. Journal of Research in Science Teaching. 42. 429 – 464. https://www.researchgate.net/publication/227658723_Promoting_fourth_graders%27_conceptual_change_of_their_understanding_of_electric_current_via_multiple_analogies
Glauert, E. (2009). How Young Pupils Understand Electric Circuits: Prediction, explanation and exploration. International Journal of Science Education. 31. https://discovery.ucl.ac.uk/id/eprint/10002194/
Ramos, M., (2011). Analogies as tools for making meaning in elementary science education. How do they work in classroom settings? Eurasia Journal of Mathematics, Science and Technology. 7 pp29-29. https://www.ejmste.com/download/analogies-as-tools-for-meaningmaking-in-elementary-scienceeducation-how-do-they-work-inclassroom-4201.pdf
IOP: Build and model electrical loops – Teaching and learning issues
IOP: Build and Model Electrical Loops: Teaching Approaches
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