There is a bloody and brutal battle being wagered in schools. Science departments are split down the middle. It's friend vs friend and the future of our children's education rests on the outcome.
Or so the educational literature would have you believe when it comes to teaching pupils about energy.
The theory goes that there are two main ways to teach energy to school children. The oldest and probably most common method is one which you may recognise from your own school days. Pupils are taught that there are seven different 'forms' of energy; kinetic, gravitational potential, chemical potential, elastic potential, thermal, light and electrical. Energy can, they are told, be transformed from one type into another, but can never be destroyed or created. When something happens, like a ball falls towards the earth, then energy is being transformed.
Now, there are some dangers associated with using this model to explain energy to pupils. They might start to assume that energy is a physical substance which magically changes from one type into another. They might also start to get confused when we explain that heat is really just vibrating particles - a type of kinetic energy - and what about nuclear energy? Sound? X-rays? Magnets?
So what is the alternative? Well we have Feynman to thank for this actually. He used the idea that energy should be considered to be a series of units, think of Lego bricks. These bricks can be transferred from one place to another, but never created nor destroyed. We can label each brick as 1 Joule. We can use the example of an electrical circuit to explain the idea: the battery has a huge store of bricks, and when we turn on the switch these bricks are transferred to the bulb by electricity where they are transferred to our eyes by light.
Energy is simply an accounting system, it shows us the ability of a system to do work and by thinking of these bricks we can really appreciate that energy is not magically transformed or altered after every change in a system.
Sounds brilliant, so why aren't all schools teaching the energy transfer method? Why is there even a debate? Well, try and explain the energy transfers in a pendulum using both methods:
|Energy is transformed
||Energy is transferred|
|At the minimum amplitude the pendulum bob is at its lowest point and moving at its fastest speed. All the energy in the bob is kinetic energy.
At the maximum amplitude the pendulum bob is stationary and at its highest point. The energy in the bob is entirely gravitational potential energy.
|At the minimum amplitude the pendulum bob is at its lowest point and moving at its fastest speed. All the bricks in the system are in the bob.
At the maximum amplitude the pendulum bob is stationary and at its highest point. All the bricks in the system are in the ... erm ... well, I suppose you could say they have been transferred into the gravitational field? Does that work?
The 'forms of energy' explanation is both clear and concise and easily assimilated into a pupils current concepts, but the 'transfer' method is neither clear nor easily assimilated, even if it is a more fundamentally accurate way of thinking. This is why there is supposedly such a fierce
debate among teachers of science.
In reality the 'energy wars' are only being fought in academic journals between educationalists who haven't been in a classroom full time for far too long. Schools have been teaching a mishmash of both ideas for ages. This combination approach is neither consistent nor ideal, but it does solve many of the problems present with using just one or the other teaching models.
The only question worth asking is: are pupils gaining a suitable understanding of what is quite a tricky area of physics?