Why it might be a good idea to learn formulae

This post was prompted by a slightly frustrating set of twitter tweets with some science teachers who were complaining that the new science GCSE specifications required students
to learn 20 formulae. Previously the formulae had been given on a sheet, presumably, available in the examination. Their views seemed to be:

It is pointless to learn something one can easily look up, or be given

That learning stuff fills up your brain with useless information

That to learn a formula would detract from understanding. Children would stress about learning the formula and not then focus on using and understanding.

It takes away precious time from the specification which is already very full, overfull possibly.

The students do not need to know the formula, they only need to be able to recognise it.

My own view is that it is good for the students as learners to commit to memory, rote learn, learn by heart – I don’t mind which phrase you use, but do not have a prejudiced response to the sometimes emotive idea of ‘simply’ learning.

It is utterly spurious to think that if we get children to learn by heart that we somehow deny them access to understanding. My contention would be that they are better served by knowing the equations than having to look them up each time.

I think that the teachers who undoubtedly do know and understand the equations are making the error that experts often make. They place too little credit on their ability to use the equations as a result of their knowing the equations.

The issue is one of the cognitive load we place on students by denying them the opportunity to learn the equations. When solving a problem there are a number of things we need our working memory to do. One of them is to keep the equation in mind. This is supported by writing it down but it is better supported by already knowing the equation to be used. The problem is likely to be one that requires the equation to be use, manipulated in some way. Why add to the cognitive load by requiring the, at best, poorly known equation to add to this load?

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