Ofsted’s crackdown on off-rolling has been under the spotlight again this week.

So far, the inspectorate has been the main driver in the education system in both defining what off-rolling is and looking to root it out through school inspection.

To recap: Ofsted’s definition of off-rolling is the practice of “removing a pupil from the school roll without a formal, permanent exclusion or by encouraging a parent to remove their child from the school roll, when the removal is primarily in the interests of the school rather than in the best interests of the pupil”.

We already know that Ofsted is tracking pupil movement to look for examples of where off-rolling might be taking place and it has identified some 300 schools where pupil movement could indicate a problem.

Last weekend’s publication of inspectors’ notes from an inspection of a secondary school last year, garnered through a Freedom of Information request, offered an intriguing glimpse about an Ofsted investigation into potential off-rolling. But they raise as many questions as they answer.  

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The documents show that, in this case, inspectors were very clearly satisfied that there was nothing inappropriate about what Ofsted described as “exceptional pupil movement” and the school in question retained its “outstanding” grade. But they are opaque on exactly how Ofsted reached that conclusion.

The handwritten notes show that inspectors questioned school leaders about the reasons for pupil departures and their destinations, and also had a conversation with the local authority. But we don’t know whether this was the extent of their inquiries.

In cases like this, do the inspectors also speak to the pupils concerned and their parents? We don’t know. If the answer was “no”, then one might legitimately pose the question as to how they can really know whether off-rolling has taken place or not.

If off-rolling is about a school encouraging parents to move their pupil from a school, then doesn’t Ofsted need to speak to the parents as well? There may, of course, be no easy or quick way of doing that - particularly not in a two-day inspection. But if Ofsted is only speaking to a school and the local authority, can it be sure it has the full story?

The watchdog is also being less than forthcoming on its system-wide conclusions about off-rolling. We know that Ofsted has identified off-rolling at three schools through inspections so far. That represents just 1 per cent of the schools it identified as having high pupil movement.

Does this mean the problem is not that common? To answer that, we would need to know how many of the 300 schools Ofsted has inspected. And to date, the inspectorate has refused to say.

The watchdog’s focus on what is a troubling issue must be welcome. But until it reveals more about its method and findings we will have no idea whether it is truly getting to grips with the problem.