There is much more behind an academic grade than a child’s computational capacity or his mastery of the 3Rs (to receive, remember and regurgitate) on a given day. It also includes his character traits and attitudes to learning, his creativity, his motivation, his levels of curiosity

Many elements of teaching and learning remain hidden. The measurements we take must not be misinterpreted as the only truth, or the law of self-fulfilling prophecies applies.

To suggest a child’s actual ability and potential can be encapsulated in his predicted grades for GCSE, or his Common Entrance results, or his row of A*s at A-level is absurd.

There is an invisible quality to the existence of things: a relationship between mass and energy, and a reaction to the environment in which things exists, that means, in theory, anything and everything can happen.

So it is with education. What lies behind an A grade in French, after all? Or a B in history? How was it achieved? This is only the visible element – the physical examination paper with etchings on it – the downloading from a term spent genning-up.

How can you give a student a B- for curiosity or a D+ for self-motivation

But the grade itself can all too often become the accepted description of the child’s ability: you are a B or a D or 120 VR or a 96 NVR.

The results of an exam cannot be attributed solely to the extent to which the pupil listened and worked hard in class, or crammed the night before. An infinite number of variables and observables are at play: his character traits and attitudes to learning, his creativity, his motivation, his levels of curiosity, etc.

It is these invisible elements that combine to create immeasurable potential in the child – and whether we know it, or like it or not, they form part of an invisible curriculum that is being taught and learned in schools every day.

In a forthcoming series of books, I talk about these invisible elements: our character, curiosity, creativity and our intrinsic motivation; the way we think; the way we communicate with each other; how we work together and depend on others to succeed. These are the lifeblood of learning: our invisible ink.

Such qualities are important inside school. They are essential if children are to reach their academic potential while preserving their emotional well-being and self-esteem. Schooling can be an arduous voyage, and it requires far more than academic competence to stay afloat.

One cannot separate the visible from the invisible curriculum; they are interconnected and interdependent. But progress in the invisible curriculum cannot be encapsulated in a grade nearly as easily as for the visible. How can you give a student a B- for curiosity or a D+ for self-motivation?

But the invisible curriculum can and should be recognised and even “taught” in schools. How? By addressing the learning environment in which the invisible learning takes place. By my reckoning, there are six key features of the learning environment in the context of each element of the invisible curriculum: teacher as model learner; the language of learning; group dynamics; choices and challenges; the element of doubt; observation.

In my new book Teaching for Character, I consider the difference between moral character and performance character. Some of the character traits and attitudes (CTAs) that lead to an effective learning performance are profiled, including grit, adaptability, optimism, self-control, empathy, discernment and trust. I offer practical advice and suggestions for how these CTAs can flourish when the learning environment is right.

The learning environment in schools, put into compartments and carefully timetabled, has for too long been dominated by the need to show academic progress via academic certification. Important though this is, few teachers would argue it is the sole purpose of education. When we consider the invisible curriculum, other important functions of school come into view: teaching children how to learn, how to think, how to live and work with others, and how to gain a greater sense of their own identity and potential.

Teaching for Character, the first book in the Invisible Ink series by Andrew Hammond, is published by John Catt Educational, £10.