Why formative assessments improve learning
A summative test measures the journey; a formative one steers it. Why low-stakes quizzing outperforms extra revision time, even when it carries no marks.
27 August 2026 1 min read
There are two reasons to test a student. One is to record what they know at the end. The other is to find out what they do not know while there is still time to fix it. Only the second changes the result, and it is the one most often skipped.
The difference in one sentence
A summative test measures the journey; a formative one steers it. The distinction is not the format, because a five-minute quiz can be either. It is whether anything changes because of the answer.
Why the testing itself teaches
Retrieving an answer from memory strengthens it more than re-reading the same material. This is why a class that is quizzed regularly outperforms a class given the same time to revise, even when the quizzes carry no marks. The act of trying to remember is the mechanism, not the score.
Making it work
- Keep it low-stakes. Marks that count turn a diagnostic into a performance, and children hide what they do not know when the stakes are real.
- Make it short and frequent. Five questions weekly beats fifty questions once.
- Act on the result within the week. A quiz that changes nothing is an administrative task.
- Show the pattern, not the mark. "Three of you missed the same step" is more useful to a class than a distribution of scores.
What the teacher gets
The real value is a corrected mental model. Every teacher carries an internal picture of who has understood what, and that picture is confidently wrong more often than it is right. A short quiz is the cheapest way to find out where.
Sources
Frequently asked questions
What is the difference between formative and summative assessment?
Not the format; a five-minute quiz can be either. The difference is whether anything changes because of the answer. A summative test measures the journey; a formative one steers it.
Should formative quizzes count towards a grade?
No. Marks that count turn a diagnostic into a performance, and students hide what they do not know when the stakes are real. The act of trying to remember is the mechanism, not the score.
How often should I run a formative quiz?
Short and frequent beats long and rare: five questions weekly outperforms fifty questions once. The condition is that you act on the result within the same week.
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