A few months ago, I had an interesting experience. I discovered that a school wasn’t allowing some of its less-able students to study what it considered to be “less important” subjects. I was then threatened with legal action by a member of staff from said school if I revealed the details.

The stakes are high when it comes to one of the biggest scandals in education today, “cohort manipulation” - the hiding, sidelining or ignoring of less-able students in favour of “driving up standards”. Or in other words, looking better as an institution at the expense of some children.

Several tools are at the disposal of those who want to covertly manipulate their own cohorts to try to achieve an “outstanding” judgement.

First, there is the “blocking” of children within the school. This occurs when students of a lower academic ability, but with natural gifts in, say, art or music, are prevented from taking those subjects. Of course, schools are now judged on Progress 8, where there is no space for design and technology, art, music or others.

By gently or forcibly stopping lower-ability students from accessing “fringe” subjects, they have a better chance of hitting targets in the “more important” ones. But as a history teacher myself, I would find it grossly ignorant to suggest history is more valuable as a subject than art. Yes, it involves more writing, but so what?

Schools need to ensure that as many students as possible are entered for the “super 8”. 

Now, while many schools feel forced into this, others actually do believe that those “super 8” subjects are superior to the arts. There are teachers out there who genuinely believe that all students, including those who are disadvantaged financially, would benefit more from maths than from art.

The second strategy in cohort manipulation occurs in the area of students with some form of special educational need or disability (SEND).

It’s been well publicised that one of the best ways to get results in the academic subjects is through chalk and talk, or direct instruction. The “get the results” aspect must be emphasised here. 

When adopted as a whole-school teaching methodology (“this is how we will teach as a school, this one way”), it leads to some interesting questions. This teaching style does involve teaching to the middle.

Now, I’m no great advocate for differentiation in all its forms, but there is no getting away from the truth - direct instruction, lecturing, chalk and talk, or whatever you want to call it, is a “one size fits all” way to teach.

So, in these schools, those with varying educational needs could suffer - especially without personal one-to-one support or more tailored materials.

But if this strategy will guarantee the success of the many, who cares about the few?

It is my contention that, in some schools, those with SEND are at best being passively accommodated and at worst forcibly ignored. I’m not suggesting that this didn’t happen in the past, but I do believe that the prevalence of Progress 8 and the rise of the “all schools should be like Eton” methodology, cohort manipulation is a trend that continues to catch on.

Thanks to the way in which our exam system is now geared - raising the status of the so-called academic subjects above all else - schools are cottoning on to the reality that, regrettably, it’s in the academic progress of the middle and higher ground where Ofsted gradings and headline figures will be won or lost.

I heard of one school recently in which staff were told that getting a student from a B to an A* was way more important than getting a student from a U to a D.

With the points weighting of grades, it makes more sense for schools to focus on the already-bright pupils than put in the leg work to raise a student up who is at the foot of the progress measures for no fault of their own.

I don’t normally get too emotive in my articles, but this underreported and often subtle focus on those children who have the potential to change the data fortunes of a school is sickening.

In a proudly “non-selective” school I know, the headlines are always the As and A*s.

In the first staff meeting of this year, they put up the names of students who got As and A*s at A level, but didn’t show how many Bs they got. A B isn’t good enough anymore. 

There was the girl who got a D in one subject, and that was the one everyone was delighted about because it got her the university place she wanted. The school cheered her place, yet didn’t publish her grades. These are just small snapshots of the bias that is embedded into our schools and our education system, helped along by government ministers and others.

It’s our duty as educators to educate the many, not the few - no one would disagree with that. However, the bigger worry at the moment is those who - whether knowingly or unknowingly - buy into the evolving status quo: “All need to be educated, but the most can help us more than the few.”

Thomas Rogers is a teacher who runs rogershistory.com and tweets @RogersHistory

For more columns by Tom, view his back catalogue

Want to keep up with the latest education news and opinion? Follow Tes on Twitter and like Tes on Facebook