I was discussing responsibilities to others with my Year 13 ethics class and we began a debate around what you should do if the person ahead of you at a cashpoint left their money behind and began to walk off down the street.

One student, a high-achiever aiming for top grades, was certain of the right response.

“I’d keep it,” they said. “If they’re such an idiot, I deserve the money.”

It was a shock. I had taught this young person ethics for nearly two years, they excelled in the subject, yet they had clearly failed to become more ethical as a result.

Part of me felt I had still done a good job: my role was to teach about ethics, not to be teaching moral behaviour. I should teach the objective material: the issues, the theories. In ethics, as much as French or history, ours isn’t to teach the values, but the facts. What he chose to do with that information, well, that was his business.

In that small example you can see the heart of a fundamental problem in schools. Our desire is to make young people the best version of themselves they can be, but it is also to let them form their own path, to guard the sacred neutrality of schools.

But here’s the thing: I really don’t think schools can be neutral. Moreover, I don’t think it would be particularly desirable if they tried to be so.

The wish to remain neutral as a school is common and it is easy to see why. We face differences of perspective every day. In our classrooms, the child of the Ukip voter sits next to the child of the Liberal Democrat voter, the Hindu sits next to the atheist. With different perspectives being brought into the classroom, teachers can rightly feel uncomfortable about being anything other than completely objective. After all, Ukip or Lib Dem, Hindu or atheist, these are all our students. Why should any student be made to feel their perspective is not valued?

Carl Bereiter, in his provocatively titled 1973 journal article Must We Educate?, defends this view. He points out that I would never let my neighbour shape my child’s beliefs or values. If my neighbour happens to be a teacher at my child’s school, he could be given licence not only to teach my child, but to work on her character. Bereiter argues that if we put our children through piano or karate lessons, what we’re paying for is exactly that: skills in piano or karate.

When we give our children over to school - and there’s no option not to, really - our children might not simply be taught “the stuff”, but might be shaped by strangers.

Why, he asks, can’t there be the schooling of the facts without the education of the values?

Many believe the two can be separated. David Hume, philosopher and key figure in the Scottish Enlightenment, argued that we can’t get “an ought from an is”. In other words, however much we look at the facts, we can’t logically work out what we ought to do: facts are different from values.

This thinking, ahead of its time as Hume so often was, gained traction in the early 20th century. Philosophers such as AJ Ayer argued that if a statement can’t be proved or disproved, mathematically or scientifically, it was literally nonsense. Ayer thought that every time we said that something was good or bad, we were simply saying we liked or disliked it.

The distinction between fact and value, established in philosophy, is embedded in how schools think of best practice. We think our job is to teach content, not to shape students with our personal values.

The ‘balanced view’ approach

Nowadays, this lack of bias is enshrined in government policy. The Prevent strategy requires all schools, by law, to teach “a broad and balanced curriculum”. It safeguards against “biased or unbalanced teaching”, stipulating that, wherever practical, any potentially political or controversial issue should be taught from both sides.

I’m more than a bit sceptical about this “balanced view” approach. Moreover, I doubt that neutrality is possible, much less desirable.

Let’s imagine what happens when we leave all values behind. Welcome to the neutral school.

A student arrives late. That lateness goes unmentioned. To comment on it would mean we’re bringing in our values of punctuality and responsibility.

A student shows dedication or kindness. No praise follows: these are values, too.

A fight breaks out in the playground, but we do not intervene: without values, who are we to admonish this behaviour?

Could we later encourage students to work hard, or to concentrate, or to finish a task? Surely not, because this would betray our belief in the values of hard graft, perseverance, grit and resilience.

Clearly, this is a ridiculous example, but it illustrates my point: trying to construct a picture of a neutral school leaves you with something that is unrecognisable.

In schools, values are everywhere. Schools prescribe when students turn up, with what, where they go, what work they undertake and when they get to go home again. Every minute of every day, we are setting expectations for students based on what the institution values.

It can even be seen in the way we set out desks in the classroom. This is something that seems so innocent, but even the arrangement of furniture can say a lot about what we value. You’ll always find tables and chairs in my classroom set out like a horseshoe. Why? Because we do lots of discussion in my lessons. Why do we do lots of discussion and why is it important to me that everyone can be included? My values are showing: democracy, individual ownership and combined effort.

A more overt way in which our values show themselves is through our expectations for behaviour. We might think of ourselves as educators, not shapers of students’ characters, but we actually do this all the time.

We do not and should not hesitate to tell a student they’re in the wrong. From the minor stuff, such as not talking over others or bringing the right equipment, to the moment we’re tackling something rude, hurtful or offensive, we are advocating certain behaviour because of the values to which we are holding students.

These overt values are everywhere, but there are subtler ways in which values affect everything we do. We’ve seen how values determine what is done. Let us now see how they determine what is not done. You can tell an awful lot about what is valued in what is left out, what is deselected from the curriculum.

When I did German A level, there was no compulsory literature element at all in my course. It seemed as though literature was out and social issues were in. Pollution, asylum seekers, the Euro and abortion played a big part in what I would be examined on.

The little I learned about German literature came from odd snatched moments between the topics on the syllabus and the vocabulary I had to learn was deeply current and relevant to modern-day social issues. All of this showed the values of the course-writers. Contemporary issues were higher up the list of priorities than German culture.

There are countless examples of this in every aspect of course selection. I call this the “absent curriculum”. This is inescapable, of course. Given finite time, something has to be left off. The point is that what’s left off tells us a lot about the values of those making the decisions.

The content of the absent curriculum changes with shifts in views. At one point, understanding British history was deemed the most important thing for students. Now, in a more globalised world, people are rightly questioning such a Eurocentric approach. Instead, students might well be studying Apartheid South Africa instead of the Plantagenets. Something has to be left out, but choices as to what that is are made based on what is valued.

The lack of neutrality embedded in all schools is not inherently a bad thing, but it is damaging if it comes coupled with a lack of transparency.

For example, a great loss comes when students are given no inkling that there is anything missing from the curriculum. Without frustrated German teachers bemoaning the fact that we didn’t have to study a book, or history teachers pointing out to students that they were learning about powerful white men only, would students realise they were learning merely some things, not everything?

The need for clarity

The same goes for how we arrange our desks or how we manage behaviour. There needs to be clarity that these are value-driven choices.

Values are everywhere, but how do students realise this if they don’t know what they haven’t been taught?

That’s one of my issues with Prevent. The instruction for a lack of bias and need for balance does not come from a neutral place at all. The whole strategy is avowedly based on “British values”, such as democracy, the rule of law, tolerance and individual liberty. The very document that requires balance and unbiased teaching is itself holding certain values to be self-evident.

This betrays a real confusion at the heart of this debate: requirements for a seemingly neutral curriculum based on a particular viewpoint, British values.

These contradictory claims are impossible to navigate: should I cover the downsides to democracy or the upsides to lawlessness? To comply with British values, I should be upholding these as central principles. To be neutral and unbiased, it seems I have to do the opposite: to look at both sides.

So let’s not strive for neutrality - it’s impossible. Let’s instead recognise that there are values everywhere in what we do at school and let’s be clear about them.

Students need to know they are studying a selection of content. They need to know that some things weren’t chosen for good reasons. Teachers and parents need to know what they are letting themselves in for when they choose to teach or send their children to a certain school.

We can’t be squeamish about values. We can’t hide them away. We can’t protect them from being challenged.

Only once we stop pretending that schools are neutral will we see the importance of giving everyone - students, teachers, parents - more choice about how and where they are educated. That should - and does - matter.

Clare Jarmy is head of philosophy and religious studies at Bedales School in Hampshire. She tweets @clarejarmy