Too many children are routinely identified as “average”, meaning their abilities - and problems - can be overlooked, a new study shows.

Researchers looking at the 50 per cent of children who are in the middle of the broad ability range found that most had a bias towards either verbal, numerical or spatial skills, meaning that only one in five (20 per cent) of children could be considered truly “average”.

And the analysis of more than 24,000 children, published by assessment experts GL Assessment, says that these biases could be behind the significant differences in the GCSE outcomes of “average” children.

The report, The Lost Middle, reveals that within the middle 50 per cent of students, only 2 per cent who had weaker verbal skills gained an A or A* in English GCSE in 2016, but for those who were verbally able, the proportion achieving A or A* rose to 33 per cent.

‘A practically useless definition’

“We should only use ‘average’ sparingly and as far as individual children are concerned not at all,” says Shane Rae, head of publishing at GL Assessment. “It’s so broad a definition, it’s practically useless.”

In the introduction to the report, Mr Rae says: “The chance of students who are generally defined as ‘average’ getting a B or above in English at GCSE range from one in 10 to seven in 10, depending on their verbal ability bias. Such divergence in performance cannot accurately be encapsulated by the word ‘average’. It is too broad to be useful.

“It won’t give the teachers the information they need to overcome learning barriers or unlock student potential.”

Similarly, the data for maths GCSE revealed that within the 50 per cent of pupils considered “average”, only 1 per cent of students who were slightly weaker numerically gained an A or A* at maths GCSE in 2016. But for those who were more able with numbers, the proportion rose to 30 per cent.

Mr Rae says: “When teachers have access to more granular information about their students, it is easier for them to identify who may be struggling below the radar and who may be capable of exceeding expectations with a bit of targeted support.”

“Of course, many teachers already know this, but while calling children ‘average’ tells us a lot about their relative strengths and weaknesses compared to other children, it tells us precious little about how an individual learns.”

Poppy Ionides, an educational psychologist, said that, while all children could be stronger or weaker in certain areas, it was particularly important for teachers to be aware of the abilities of children who appeared “average”.

“One could argue that we should ask the question of all scores, not just average ones,” she said. “But for those children who sit in the comfort of the mid-range, it is often not seen as relevant to look behind and beyond scores. However, each average score is part of a unique life story for which the future is all to play.”

Want to keep up with the latest education news and opinion? Follow Tes on Twitter and like Tes on Facebook