In education, there are many ways to win a debate, but one method has recently emerged as more effective than all others: counting the “opportunity cost” (OC).

The concept of OC suggests that if you adopt one method of doing something, there could be a cost, because another method might have offered a more effective and efficient use of resources. It is generally used as an argument against playing games or making posters in class, as well as more contested activities such as questioning or group work.

We all want to make the best use of the time we have in class, so it’s unsurprising that many in education have seized upon the term; you are likely to have heard it mentioned after an observation, in a staff meeting or on Twitter. But look closely at OC and you find it’s not the royal flush for education debates that people make out. Worse, it could actually be damaging.

A failed interpretation

The concept of OC originated in economics or, more specifically, microeconomics, where it is linked to the idea of scarcity. Scarcity is the problem that arises when the unlimited wants of a population (nice food, a big house, Ferraris for all) are restricted by limited resources (labour, capital, time). To help decide how best to allocate resources, an economist might carry out an OC analysis - a systematic method of weighing up the pros and cons of two alternative courses of action.

It’s easy to draw parallels with education. We all want our schools to develop core knowledge and soft skills; to produce world-beating academics, artists and athletes; to foster selfesteem and reduce social inequality and generally bring about a more harmonious state of world affairs. But there are only so many hours in the day (scarcity), and we teachers play a small but significant role in deciding how we should spend this time (opportunity). We also know that some practices are more effective at achieving certain ends than others (cost).

Originally, the transfer of the term OC from economics to education was quite straightforward. On the rare occasions when OC was mentioned in educational circles, it was in purely economic terms - the OC of smaller class sizes, for example. The financial consequences of smaller class sizes mean an OC analysis is entirely appropriate.

Similarly, OC is well-suited to the debate on teacher workload, where the hours teachers spend doing various activities can easily be totted up. When a minister or school leader announces what they believe everyone should start doing next, it is entirely reasonable to reply: “And what would you like us to do less of?”

However, many of the contexts in which OC has been applied relate to curriculum and pedagogy, and here OC has started to make itself a little too comfortable in the education debate. There are a number of reasons for politely but firmly ejecting this intruder from our classrooms. Here are four of the main ones.

1 Impossibility of implementation

Suppose you wanted to calculate the OC relating to whether to meet and greet your pupils at the door. First, you would have to make a decision about how you wanted to measure the “cost” of each alternative. That would depend on a range of factors. When did you last see the class? Do you have lots of material to cover before an upcoming exam? Are there students who will benefit from a kind word as they enter the room? Is “meet and greet” a whole-school expectation? It’s far from simple.

If we were to be fully OC-aware teachers, then we would have to go through this process for everything we did, not just those decisions deemed worthy of debate on social media. And that would be difficult. Educationalist Ted Wragg once estimated that teachers make more than 1,000 evaluative decisions on any given school day; others claim it is more than 3,000. Attempting to carry out a systematic cost-benefit analysis for even a fraction of those decisions would clearly be absurd. What’s more, there would be a serious OC associated with spending so much time carrying out OC analyses. You would disappear into a hole of your own making before you could say “scarcity”.

2 Limits on your repertoire

Which kind of teacher is most likely to be able to cater for the diverse needs of all the students in their care: one who is able to draw upon a range of strategies in response to a range of contextual demands, or one who dismisses entire pedagogical approaches in the name of OC? I know whose class I would rather be in.

3 Ideological objections

When OC calculations are applied to educational settings, they are quickly subsumed by the values that teachers place on different courses of action within the contexts of their professional lives. As such, any reference to the notion of cost as shorthand for the objective worth or impact of any educational practice is hopelessly simplistic; it masks a dizzying array of assumptions that quietly undermine efforts to reach definitive conclusions.

And the way in which OC is increasingly employed as an argument for rejecting a range of educational practices (many of which are backed by compelling evidence as to their academic utility when used effectively) suggests not so much a practical cost-benefit analysis of competing alternatives, but a manifestation of ideology and values. That, and a selective reading of research literature.

4 Risk of stagnation

In universities, there are essentially two kinds of research: that which responds to what has gone before, and that which seeks to break new ground. Since the one thing almost everybody agrees on is that there is room for improvement in our education system, it is important that teachers do not feel cowed into limiting their repertoire in the name of OC.

One only need look at the progress of aviation throughout the 20th century - from catastrophic early attempts at manned flight to half a million people being airborne at any one time - to realise that using OC as a reason for sticking only to tried and tested methods is short-sighted.

We as a profession should continue to innovate and take risks, where appropriate, and to make educational ideas work better where their forerunners may have fallen short. The alternative to innovation is stagnation, and who would argue for that?

The New York Times recently reported that most economists don’t really understand OC. If this is true of economists, it is even truer of teachers.

While the language of OC might masquerade as objective evaluation, in reality, it should be seen as a divisive rhetorical device that is used to apply a binary yesno filter to a range of complex, nuanced contexts. The opportunity cost of disregarding useful strategies on the basis of OC is vast. By the very logic of OC, teachers should refrain from using this simplistic and unhelpful term.

James Mannion is lead professional for science at Varndean School in Brighton and a doctoral student at the University of Cambridge