What is diagnostic assessment in primary-school maths?
By the BrightHop team · Published · Updated
Short answer
Diagnostic assessment is a check designed to find out what a child knows and what they are missing, so the next step can be chosen. Its output is not a mark but a description of the skill that needs teaching. It differs from a test that ranks or grades.
Definition
'Diagnostic' here means finding the cause of a difficulty. A diagnostic question is chosen so that different wrong answers point to different problems. A good one tells you why an answer was wrong, not just that it was.
Diagnostic, formative and summative
| Type | Question it answers | When | Example |
|---|---|---|---|
| Diagnostic | What exactly is the gap? | Before teaching | A short check on one topic with varied question forms |
| Formative | Is the teaching working? | During learning | Asking a child to explain, a quick retest |
| Summative | What has been achieved? | At the end | An end-of-term test or NAPLAN |
The three overlap. Research on classroom assessment by Black and Wiliam (1998) is the usual starting point for the case that using assessment to guide teaching, rather than only to grade, improves learning.
Example
- Answer 3: the child knows the pair.
- Answer 17: the child added 7 and 10. The idea of a partner to make a whole is missing.
- Answer 2 or 4 (pairs that make 9 or 11): the child is close but not checking the total.
Each wrong answer suggests a different next step. A plain right/wrong mark hides that.
What parents can do with it
- Run a short check on one topic, not a long test across everything.
- Look at the pattern of mistakes before the score.
- Teach the missing skill, then re-check with new questions.
BrightHop's free Skill Checks are built this way, as informal checks to help decide what to practise. They are not formal assessments and do not replace a teacher's judgement.
Try it
See what a short diagnostic-style check looks like. The free Skill Checks take about three minutes, with no account.
Browse the free Skill ChecksFrequently asked questions
Is NAPLAN a diagnostic assessment?
NAPLAN is a national assessment of literacy and numeracy at particular year levels. Its results can show areas of strength and need, but it is a point-in-time assessment, and any follow-up diagnosis of a specific skill is up to the school and family. See ACARA for what NAPLAN covers.
How long should a diagnostic check be?
Short. Five well-chosen questions on one topic can show a pattern. Long tests tire children and blur the picture.
Related guides
Sources
- Inside the Black Box: Raising Standards Through Classroom Assessment (Black & Wiliam, Phi Delta Kappan, 1998)
- NAPLAN (ACARA)
This guide is written by the BrightHop team from BrightHop’s own teaching approach. It is not independent research and not official curriculum guidance. Curriculum and research statements link to their original sources above. Skill Checks are informal and do not replace a teacher’s advice. About BrightHop