Do students choose subjects based on how hard they are graded?

charles blog post grading pic cropped

This is the second of three blogs in which I am discussing the problems arising from variable grading severity at A-level. In the first, I made the point that the current lack of comparability needs to be addressed urgently, mainly because it puts up barriers to free, optimistic and valuable choices at A-levels.

In this blog, I will look in more detail at how those barriers arise, how they fetter choice and how they have distorted the whole qualification system at level three.

We know that, at A-level, physics is graded more severely than English, history and psychology. Furthermore, schools and students are aware of these differences because they have access to a predictor system. This system tells them their likely outcomes in different subjects from a given set of GCSE results. It uses exactly the same historic performance data that show that physics is graded severely. Therefore, for a typical set of GCSE grades, a student will nearly always be predicted a lower grade in physics than in psychology, for example. The only exception being a candidate with straight A* grades at GCSE.

This knowledge, combined with other structural elements, has a number of adverse effects, including:

  • Restricting students’ choice of A-levels

  • Reinforcing the myths about subject difficulty (or ease)

  • Distorting the intake to A-level subjects

  • Distorting the way in which grades are used

Let’s look at these in more detail.

Restricting choice

We know that some kind of restrictive filtering is taking place. Tom Allen has blogged on the data showing this effect. He included a graph that shows the number of school sixth forms that have only candidates with A*/A at GCSE taking each of the facilitating subjects at A-level.


There are 720 schools that have no-one taking physics A-level with a B grade or less at GCSE. In contrast, there are only 125 schools with the same pattern in history. It is highly unlikely that this disparity has arisen by chance.

Either students with lower grades are being edged away from physics – through dissuasion or different entry requirements – or they are self-selecting themselves out of it.

Let’s examine these two mechanisms.

Student behaviours (self selection)

When students make their choices, they will be based on their interests, enjoyment, future plans, and so on. But, above all, many of them will be influenced by the likely success in the subjects they choose. This would be fine if a student with uniform prior attainment (say all B grades at GCSE) were predicted the same grades in A-level psychology as in A-level physics. But this is not the case. In fact, they will be predicted one grade lower in physics than in psychology. This is bound to deter them from taking physics – however much they enjoy it.

There are many students who enjoy physics, have been successful at it and would benefit from taking the A-level, but they are drawn to a less appropriate subject by the promise of a higher grade. And this higher grade is based on the inequitable differences in grading. Therefore their decision has been directly affected by a broken system.

School behaviours (edging students away)

The same predictor is used by schools who know that their performance is measured, in part, by the number of high grades that their students gain at A-level. It is therefore in a school’s interest to have students embark on subjects in which they are more likely to get high grades. This can lead to a number of detrimental behaviours. The school might:

  • Require higher grades on entry for physics, maths etc than for other subjects

  • Not offer those subjects subjects at A-level

  • Subtly dissuade students from taking the more severely graded subjects (with references to them being difficult)

Reinforcing the difficulty myth

Physics has, for some time, had a reputation for being difficult. And having this reputation is a problem. It is also underserved. The notion of it being difficult is based on many ill-defined facets that play into each other. I will discuss them in my third blog. But, in short, they are all myths and they can be dispelled with a little thought.

Nevertheless, the existence of different entry requirements to begin the A-level in different subjects stokes the reputation that some subjects have for being more difficult. And compounds the likelihood of students opting away from those subjects. Even students who achieve the required entry grade can be deterred from choosing a subject which is somehow exceptional in its requirements. They absorb the message that physics, maths and the other sciences are for an elite and they cannot imagine themselves to be a part of that elite.

Reinforcing the easy myth

It is worth noting that the differences in grading severity have also had an adverse effect on subjects that are graded less severely. They are seen as being too easy for the more academic students in the school and are not always taken seriously by higher education, employers or the media. Some students will be guided away from these as much as others are guided away from those that are graded severely.

Distorting the intake

Let’s return to the grade predictor I mentioned above. There is one set of students who will be predicted the same grade for physics A-level as psychology A-level: those who have (or expect to have) all A* grades at GCSE. Therefore the students who are most likely to stick with physics, having seen their predicted grades, are those who have all A*s at GCSE. Consequently, the intake to physics is skewed: the prior attainment of those starting an A-level in physics is higher than that for psychology and also for English. Interestingly, the distributions for maths and physics are almost identical. The modal intake grade for maths and physics is A (accounting for 41% of the intake). 53% of maths and physics students average A* or A across their GCSEs. For psychology, about 3% of students average an A* and the modal average grade is B, as it is for English with 38% coming in with A* or A average grade.


This skewed candidature exacerbates the subject’s reputation for being difficult and, unhelpfully, reinforces the notion that it is the preserve of an academic elite.

Furthermore, the skewed intake makes it more difficult to address the problem of grading severity (because doing so would further overload the top grades).

Distorting the use of grades

The skewed intake means that students are not distributed across the grades in the normal way.


The modal grade for physics is A/A*. Contrast the physics distribution with that for English – which is closer to a normal distribution.

To some extent, physics has become seen as a gateway subject for higher education, and practically all physics A-level students do go on to a first degree at university – for which only the top grades have utility. Consequently, physics is no longer seen as a genuine option for students who will get a lower grade and/or leave academic education at 18. This lack of genuine use of the lower grades is regrettable for two reasons. It means that:

  • A lot of students are missing out on the benefits of a physics education at A-level – because they feel that it is only for those aiming for academic degrees

  • The lower grades are being populated by downgrading middle grade students – as is shown by the more severe grading at C/D level (thanks to Ronan for pointing this out under the previous blog)


Inequitable grading severity has prevented students from making a free choice; it has damaged, in different ways, the reputations of the subjects that are either severely or laxly graded, and it has led to students being corralled into subjects based on their prior attainment.

It is important to address the regulations so as to get an equitable grading system that allows schools to nurture the interests and abilities of students and have them fairly recognized by their final grade.

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Charles Tracy

Charles Tracy

Charles is the IOP’s head of education. He came to the Institute in 2006 after 12 years as a physics teacher, including two as head of physics and three as head of science.
Charles Tracy

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