Children in the UK are assessed, examined and tested to an exhausting degree, yet we know that measuring the pumpkin or weighing the pig does not in itself bring about any improvement. At the same time, it is clear that at least some measurement of pumpkin or pig is useful for keeping track of what works best.
School management information and communications technology has progressed at a rate that means heads and teachers now have the ability to collect and handle huge amounts of data about their pupils. How, though, to make it work for school improvement?
One school that has found a working answer is Two Mile Ash middle (pupils aged 8 to 12) in Milton Keynes, where head Jim Hudson OBE runs a highly successful school that, in his words, is "Data informed - that's the phrase I prefer, rather than data driven or data rich."
The point being that the data is to do with asking questions rather than providing solutions.
"The software doesn't make things happen," says Mr Hudson. "You have to ask the right questions. Being expert with the ICT isn't as important as asking where we're going wrong, learning lessons year by year."
At Two Mile Ash, children are tested twice a year, in a formal but friendly way, using Sats material, including optional tests and tests from previous years.
Papers are marked in school, and because the quality of the marking ultimately defines the value of the data, there is careful moderation between teachers.
"We didn't put the writing scores in one year, because we weren't convinced of their accuracy," says Andrea Curtis, deputy head. "Moderation had to be done thoroughly - you have to give time to it, or you'll come unstuck."
The data that emerges is entered into the school's information management system (the school uses SIMS Assessment Manager from Capita) by an administrator. It is then handled by four teachers who make up the data analysis team. Overseeing the whole process is deputy head Andrea Curtis.
"The head will be expecting a report as soon as possible about the headlines, in both attainment and progress," she says. "Too many people talk only about attainment. It's more important to talk about progress. I give him the profile and the value added for each year group."
At departmental level, she explains, heads of department look at individual teaching groups. "They want to see how each group is performing, to see what we can learn - where we might need to target more resources, for example."
The implication here, of course, is that a comparison of group performance throws up differences in quality of teaching. "It's not a question of criticising the teacher," says Mr Hudson. "You need honest self-evaluation and to look for the strategies that will improve things."
Ms Curtis gives the example of a relatively inexperienced teacher whose teaching groups were shown by the data to be weaker on high-level literacy skills.
"We were able to put in support systems and organise lesson observations," she says.
The key presentation document is the scattergram - a graph from Assessment Manager which, because it presents individual children as dots positioned according to their test performance, clearly shows up individual differences. The test and data analysis procedures at Two Mile Ash mean that each subject teacher is given one of these for each of his or her teaching groups, twice each year.
"It's a great management tool," says Mr Hudson. "Without it you couldn't question to such depth, being very specific about what you're trying to discover about teacher and child performance."
As time has gone on it turns out that the scattergrams confirm teacher judgements to the point where a teacher can name the anonymous dots almost at a glance. "It empowers teachers, reassuring them that their professional judgements are secure," says Ms Curtis.
In the same way, there is added confidence and detail in the judgements offered to parents. "I want them to feel I know what I'm talking about," says Mr Hudson.
Both Jim Hudson and Andrea Curtis are at pains to emphasise that at the heart of Two Mile Ash is the teacher-pupil relationship, and that computer software is only useful to the extent that it enhances that relationship.
"We're cautious and selective about ICT," says Mr Hudson.
And when Ms Curtis speaks, as she often does, to groups of teachers and heads interested in the constructive use of data-handling software, it is significant that one of her slides says: "Strategy does not begin with technology. Teachers raise standards, not computers."
Two Mile Ash middle school uses Assessment Manager from Capita: http:home.capitaes.co.ukOther products are available. For a list, see Becta's website: www.becta.org.ukleadersdisplay.cfm?section=3_3