We think our foundation stage pupils have made good progress, but our School Improvement Partner tells us it’s just satisfactory. Any advice?

The figures you quote in your full question to me don’t provide enough information to tell. Two levels is the expected progress over the course of key stage 2 so, in that sense, it would appear to represent satisfactory progress. However, just measuring whole levels is a rather crude and imprecise way of gauging progress.

You will get a clearer picture of the progress pupils are making by looking at the sub-levels. A pupil who attained level 2a in KS1 and who is assessed at level 4c at the end of Year 6 has made relatively slow progress.

By contrast, pupils who were level 2c in their Year 2 assessments who go on to reach Level 4a have made much better progress. In fact, the second will have made twice the gains of the first (eight sub-levels as opposed to four). This illustrates why referring just to whole levels can give you a deceptive picture.

There are other pitfalls. Inspectors will be aware of the ceiling effect. KS2 tests do not measure beyond level 5, so it isn’t practically possible for an able pupil who scores level 3a in Year 2 to go beyond level 5a in Year 6. That doesn’t mean that these pupils would be described as having only made satisfactory progress.

A measure that many schools use is to expect each pupil to make two sub-levels progress each year. If consistently achieved, that is likely to represent good or better achievement. I say likely to because the circumstances in each school differ. It is possible, for example, that progress in some year groups may look strong, but only because pupils have underachieved in previous years.

If you rebase your targets each year - merely adding two sub-levels to whatever level the child reached at the previous year end - then there is a risk of you giving yourself a distorted picture of how well the pupils are doing over their time at the school. Though it is not an Ofsted term, I refer to this as the risk of institutionalised underachievement. Expect inspectors to look carefully at progress over time

Selwyn Ward has been an inspector for 15 years, working in primary and secondary schools. The views expressed here are his own. To ask him a question, email him at features@tes.co.uk.