Testing a child's reasoning is a different exercise from testing an adult's, and not by a small margin. A nine-year-old and a twelve-year-old at exactly the same percentile will answer wildly different numbers of items correctly, because the whole scale is rebuilt for each age band. Hand a child an adult format and the figure it produces is not merely imprecise - it is measuring against the wrong population entirely.
This page covers how age-norming works, what the established children's instruments actually assess, where free online versions are useful and where they mislead, how to read a report without over-reading it, and how to talk to a child about a result. Parents arrive at this topic for very different reasons - school has raised something, a child seems bored, a diagnosis is being explored - and the answers differ depending on which.
Why Children's Scores Are Age-Normed
Adult performance on reasoning tasks is broadly stable across a wide span of years, so a single conversion table covers most of adulthood. Childhood is the opposite: capability changes rapidly, and the difference between a seven-year-old and an eight-year-old is enormous in absolute terms.
Age-norming solves this by comparing each child only with others of the same age. Professional instruments band norms to within a few months for younger children, because half a year at that stage represents substantial development. A raw score is converted using the table for that exact band, and the result answers one question: how does this child compare with peers of the same age? Nothing more.
Two consequences follow. First, a child's standardised score is expected to stay roughly constant as they grow, even though their absolute ability rises steeply - the reference group is rising alongside them. Second, any assessment that does not ask for a precise date of birth cannot be age-normed and cannot produce a meaningful figure for a child, whatever it displays afterwards.
What the Main Instruments Measure
Professional children's assessment is dominated by a small number of well-documented batteries, each with a defined age range and its own structure.
| Instrument | Age range | Structure | Typical use |
|---|---|---|---|
| WPPSI | Roughly 2.5 to 7 years | Play-based subtests, verbal and non-verbal | Early years assessment, school entry questions |
| WISC | Roughly 6 to 16 years | Five index scores plus a full-scale composite | The standard school-age battery |
| Stanford-Binet | 2 years to adult | Verbal and non-verbal domains across five factors | Wide age span, strong at the extremes |
| Raven's matrices | Child and adult forms | Non-verbal pattern reasoning only | Language-independent screening |
The WISC deserves particular attention because it is what most UK school-age reports are based on. It does not produce one number in isolation. It produces separate index scores for verbal comprehension, visual-spatial reasoning, fluid reasoning, working memory and processing speed, and only then a composite. Those five figures are where the useful information lives. A child with strong reasoning and slow processing speed will show a depressed composite that hides the actual profile - which is precisely the sort of pattern a report is meant to reveal.
Ages Seven to Thirteen: What to Expect
This is the band where most parental interest concentrates, partly because school assessment tends to happen here and partly because children this age can sit a structured session without it becoming an ordeal.
- Seven to eight - sessions are short and heavily supported. Instructions are demonstrated, and the assessor is watching engagement as much as accuracy.
- Nine to ten - most children can sustain a full battery with breaks. Reading demand starts to matter, so a weak reader can look weaker than they are on verbal sections.
- Eleven to twelve - the age at which formal selection testing often appears in the UK. Familiarity with question formats has a real effect here, independent of ability.
- Thirteen and above - approaching adolescent norms, and motivation becomes a genuine variable. A disengaged teenager will underperform substantially and consistently.
Motivation is the factor most often left out of the conversation. Adults sitting an assessment usually want a result. Children frequently do not, and a child who has decided the whole thing is pointless will produce a figure that measures their mood. Any assessor worth using notes this in the report rather than reporting the number as though it stood alone.
Free Online Versions: Useful and Misleading
There is a legitimate role for informal online assessment with children, and it is narrower than the marketing suggests. Where it works: as a low-stakes way for a curious child to meet puzzle formats, as a rough indicator of whether a formal assessment might be worth pursuing, and as an enjoyable activity for a child who likes patterns.
Where it fails: anything consequential. School placement, gifted programme applications, learning-difference identification and any clinical question all require a supervised battery administered by someone trained to interpret it. A home session cannot substitute, and a school will not consider it.
Two specific traps are worth naming. The first is age-norming, already covered - most free formats apply adult tables to whoever sits them, and a ten-year-old measured against adults will produce a discouragingly low figure that means nothing. The second is ceiling and floor. A short item set cannot discriminate at the extremes, so it will misplace exactly the children whose parents are most likely to be looking. If a home session is going to happen at all, it should be one with published age bands and a clearly stated range - the same properties that distinguish a genuinely accurate IQ test for adults.
Presented sensibly - "these are pattern puzzles, let's see how far you get" - a well-built iq test in matrix format is a pleasant hour for a child who enjoys that sort of thing. Presented as a verdict, the same session can do lasting damage to how a child thinks about their own capability.
Reading a Report Without Over-Reading It
A professional report runs to several pages and the composite score sits somewhere in the middle of it. Reading it properly means resisting the pull towards that one figure.
- 1
Start with the index scores
Five numbers describe a profile. Their spread matters more than their average, and a wide spread is itself a finding.
- 2
Find the confidence intervals
Every score comes with a range. A composite of 118 with an interval of 113 to 123 is not distinguishable from 122.
- 3
Read the behavioural observations
The assessor's notes on attention, fatigue, anxiety and engagement explain more anomalies than the numbers do.
- 4
Check which composite is emphasised
Where processing speed or working memory is unusually low, assessors often report a general ability index instead, and will explain why.
- 5
Go to the recommendations
This is the part that changes anything. Everything before it exists to justify what the assessor suggests doing next.
If a report offers a number and no recommendations, it has been half done. The purpose of assessing a child is to decide what to do differently, not to file a figure.
Talking to a Child About the Result
Children absorb labels quickly and hold them for a long time. A child told they are exceptionally clever often becomes reluctant to attempt anything they might fail at, because failure now threatens an identity. A child told they scored below average frequently stops trying at all. Both outcomes are well documented and both are avoidable with reasonably careful language.
What works is describing the profile rather than announcing a rank. "You are quick at spotting patterns and you take your time with words" is accurate, useful and carries no verdict. It also happens to be closer to what the report says than any single number is. If the assessment was arranged to answer a specific question - about school pace, about a suspected difficulty - explain that question and its answer, and leave the composite out of the conversation entirely.
It is also worth saying plainly that the result describes now, not later. Standardised scores are reasonably stable but they are not fixed, and effort, teaching and time all move what a child can do. That framing keeps the finding useful and keeps it from hardening into something a child carries around. The same clear-headed reading of numbers runs through the material published by Virgin Games on probability and reasoning - and for adults curious about their own figure, the practical starting points are covered in the material on sitting a free IQ test online, on what qualifies for the Mensa IQ test, and in the breakdown of IQ test questions.
More on IQ Testing
Continue with the rest of the material on assessment, scoring and question formats:
