In many secondary schools today, data has become the defining feature of academic life: produced, analysed, colour-coded, inspected, compared, shared and, too often, weaponised.
Numbers have taken on an authority that feels absolute, as anyone who has had to sit through the horrors of a results analysis meeting can attest.
Yet behind this veneer of precision lies a troubling reality: data can be shaky, incomplete, reductive and far less meaningful than we pretend.
A narrow definition of ‘data’
Part of the problem is that schools have adopted a narrow working definition of data. In practice, “data” tends to mean numbers on a spreadsheet: test scores, baselines, targets, progress indicators and so on.
To define progress merely as an increase in numbers on an Excel document is to mistake the map for the territory. It offers an illusion of completeness, while missing the profound complexity of “the whole child”.
Real educational data is far richer and more textured than this.
It includes teacher judgement, refined through years of experience. It includes student context, such as bereavements, upheavals and personal passions. It includes character, resilience, intellectual curiosity and the ability to collaborate, persist and reflect.
Dangerous assumptions
Another uncomfortable truth lies beneath our fixation on data: no one fully agrees on what learning or progress actually is.
Cognitive science has made great advances, but the mechanics of internal schema-building, conceptual integration and long-term retention remain only partially understood.
Because learning is invisible, we rely on proxies. And data provides a very comforting one. We can look at a rising graph line and reassure ourselves that learning must have occurred and we are doing a “good” job.
But proxies can mislead. A higher test score may reflect short-term memorisation, not deep understanding. A lower baseline may reflect nerves, not potential. A “below target” label may reflect nothing more than a flawed starting point.
The danger is that data offers a comforting illusion of certainty in a domain that is inherently uncertain.
A product of the system
Of course, data is most prevalent around assessment - but this, too, is notoriously unreliable.
A target grade for the whole year, GCSE or A-level course is often generated by what a student achieves in a short multiple-choice test at an arbitrary point in the Christmas term - perhaps on a bad day, in an unfamiliar room or under conditions that did not reflect the child’s actual potential.
Yet that baseline is converted into a prediction, which becomes a target, which becomes an accountability measure.
Although it is tempting to blame senior leaders for all of this, the reality is it is a product of the system we inhabit: where schools are judged on performance tables, inspectors expect to see quantifiable progress and accountability rewards numbers over nuance.
Leaders, operating within this framework, inevitably build internal systems that reflect external pressures.
As such, the overreliance on data is not always a failure of leadership. It is a consequence of the environment that leaders are required to survive in.
Distorting decisions
But while the system may explain the problem, it does not make its consequences any less troubling.
A student might be withdrawn from subjects they find difficult - or even ones they love - because of fears their final grade will drag down the school’s assessment outcomes.
Interventions may be targeted not at those who need them most, but at those who sit just below a performance threshold that influences the school’s headline figures.
All of this rests on a deeply flawed assumption: that the primary value of studying a subject lies in the grade achieved at the end and, therefore, the data point it represents.
Teaching to the test
The effect of these pressures is clear. Curriculum time is dominated by exam practice. Schemes of learning narrow. Extended reading disappears.
Creative tasks are sacrificed for predictable ones. Teacher autonomy shrinks. Decisions are made based on fear, not love. Students learn to perform rather than think.
It flattens subjects into exam techniques and reduces learning to what can be weighed and measured.
Towards a healthier relationship with data
Of course, data has a place in education.
It can identify misconceptions, spotlight inequality, evaluate interventions and ensure that no child slips through unnoticed. However, it must be a servant of professional judgement, not its master.
To move forward, we need to expand our definition of data, rehumanise our understanding of progress and recognise that the most important parts of education - curiosity, confidence, resilience, inspiration - are not captured in numbers.
Above all, we need to revisit that old aphorism: the pig does not grow fatter because we keep weighing it. It grows because someone feeds it, cares for it, understands it and sees it as more than a data point.
Mark Zacharias is head of English and head of senior scholars and Oxbridge at Stamford Schools
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