The title of this blog is often attributed to Lord Kelvin, professor of natural philosophy (physics) at the University of Glasgow for the second half of the 19th century. As with many quotes used in popular culture, there is no evidence he said these words, although the sentiment is the same as the longer quote which he did.
“I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be.” (Thomson, 1889)
When it comes to Scottish education, we have precious few independent objective measures. For most of the last two decades we have only participated in the PISA (Programme for International Student Achievement) assessments for 15-year-olds, although we have recently rejoined PIRLS (Progress in International Reading Literacy Study) and TIMSS (Trends in International Mathematics and Science Study) which assess reading, maths and science for younger pupils, but have not yet seen any results. Within Scotland we abandoned the Scottish Survey of Literacy and Numeracy (SSLN), and the previous Scottish Survey of Achievement (SSA), which sampled pupil outcomes across schools replacing it with the Scottish National Standardised Assessments (SNSA). These assessments are only of literacy and numeracy and do not assess domains beyond these. This is a reasonable starting point as proficiency in basic arithmetic, and especially in reading, are the foundation needed to access the whole of the rest of the curriculum, however, developing reading comprehension then depends on a good general knowledge across all curriculum areas.
The adoption of the SNSAs changed the emphasis of national assessments to one much more reliant on teacher judgement both in the assessments themselves but also the timing of the assessments. This is made clear in the Scottish Government website describing these assessments:
“The assessments help to identify children’s progress, providing diagnostic information to support teachers’ professional judgement.”
and:
“Once assessments have been completed, a diagnostic report is generated for individuals and groups of learners. When considered alongside a wide range of assessment evidence, the information provided by the assessments is used by teachers to plan next steps in learning and to help inform their professional judgements about learners’ progress. The reports provide indicative information, based on learners’ assessment responses, identifying strengths and areas that require further support.”
Now, I am not saying that teachers should not gather diagnostic or formative assessment evidence of how their pupils are performing, I would argue that this is something teachers should be doing all the time as part of teaching. However, a national assessment for this purpose is an entirely different thing to gathering assessment evidence about how an education system is performing overall, and I would argue that to try and do both with the same assessment instruments and processes is not possible, and results in neither being done well. We should always be clear about the purpose of an assessment and design it accordingly.
I do not know of a teacher who does not want to see the best for their pupils. There is a natural tendency for teachers to give pupils they know well the benefit of the doubt and it is easy to succumb to pressure to inflate results due to the accountability culture prevalent in Scottish education. This is almost certain to lead to grade inflation. An obvious example of this was the significant increase in grades awarded in 2020 and 2021 when the COVID-19 pandemic resulted in National Qualifications awards being based on teacher assessment rather than the traditional diet of examinations (Holden, 2021, Lewis and Bolton, 2022). To counteract this natural tendency, it is important we have objective national assessment of pupil outcomes, as it is only by gathering such data that we will be able to determine whether educational reforms have been successful.
Many will argue that education is a complex field and the use of independent, objective assessment is a blunt instrument which will lead to unintended consequences, but the alternative to the gathering of such measurements condemns us to relying on opinion which I would argue is a far worse option. Thomas Guskey describes this scenario well with his five levels of data (Guskey, 2016). If we are to draw worthwhile conclusions about the effectiveness and efficacy of any reform, we must gather level five evidence from objective assessment of pupil outcomes, otherwise we will be swayed by lower-level information driven by teacher opinions. These opinions will always be subject to factors such as the ‘sunk cost fallacy’ where teachers continue to proceed with less effective reforms influenced by the time and effort already invested in them or by placebo effects due to the fact that investing time and effort into any initiative will likely result is some change, even if this is similar or less than might have been achieved by ‘business as usual’. Dylan Wiliam has frequently expressed the view that
“Most leaders try to improve schools by looking for unproductive things to stop doing. There aren’t enough of them to make a difference. The essence of effective leadership is stopping teachers doing good things, to give them more time to spend on even better things.” (Wiliam, 2018).
Without objective assessment of pupil outcomes, we will never be able to identify the ‘good things’ from the ‘even better things’.
The 2025 PISA data have confirmed a trend that had already been emerging from previous rounds of assessment, see this previous blog. The PISA scores of countries, including Scotland, Finland, New Zealand and Wales, which have gone down the route of skills and competency-based curricula continue to drop. However, countries such as Singapore, Estonia and England which have more clearly specified knowledge-rich curricula have bucked this trend by holding steady or even improving; scores countering the overall downwards trend of the OECD average. There are many well documented explanations for this (for example, Hirsch, 1999, 2016; Willingham, 2009; Surma et al., 2025; Paterson, 2026) and from the largest ever educational study, Project Follow Through (NIFDI, 2024), which few in Scotland seem to have heard about. I now consider we have gone beyond correlation towards causation, with our increasing understanding of cognitive science providing the explanatory mechanism. Despite this large and growing body of evidence, it is sad to see many in different jurisdictions around the world develop contorted arguments to try and explain away evidence which does not agree with their world view of education and learning, or just dismiss the evidence as irrelevant. I see many in Scottish education, brought up on a romantic diet influenced by the thinking of the likes of Dewey and Rousseau, struggle to adapt to the increasing body of evidence which conflicts with their view of education and the discourse that has dominated Scottish education during this century.
New Zealand has already revised its curriculum to one that builds knowledge and practices through a more clearly specified progression, and Scotland’s Curriculum Improvement Cycle is heading in that direction, at least compared to our existing curriculum. But, as the maritime analogy states, it takes a while to turn around an oil tanker, and education always has its own inertia thanks to it operating on annual cycles and it taking up to fifteen years for a pupil to pass through the school system. Scottish education has now been heading in a particular direction for so long it will inevitably take a lot of effort to turn it, but having good independent objective assessment evidence will be an important part of that process. Where such evidence runs strongly against the long-accepted stance of many, it will nevertheless take time and effort to win over hearts and minds. Assessment statistics alone will not be enough. For many, direct evidence of improvement in day-to-day outcomes for pupils in classrooms will also be needed. Many teachers will need to see close colleagues enact change successfully and need support and encouragement to enact similar changes themselves. As Lawrence Stenhouse said, “all curriculum development rests on teacher development” (1975).
Therefore, having good assessment processes is only one piece of a more complicated jigsaw which also includes introducing a well-designed, clearly specified national curriculum, a relentless focus on improving the instructional core in classrooms, well-facilitated knowledge exchange networks to allow actors within the system to share good practice and resources amongst themselves, and perhaps most importantly a culture which allows open and honest discussion of what for many may be difficult and contested issues without fear of reprisal.
Too often there has been a cosy consensus in Scottish education which has stifled creativity and driven people towards a safe mediocrity, a description which might now also apply to our PISA scores. Our young people deserve better, as do our teachers as they are the means through which we can achieve more for our pupils.
References
Guskey, T. R. (2016) ‘Gauge impact with 5 levels of data’, Journal of Staff Development, 37(1), pp. 32–37. https://uknowledge.uky.edu/cgi/viewcontent.cgi?article=1059&context=edp_facpub.
Hirsch, E. D. (1999) The schools we need and why we don’t have them. New York: Anchor Books.
Hirsch, E. D. (2016) Why Knowledge Matters. Cambridge, MA: Harvard Education Press.
Holden, J-P. (2021) SQA results: Drop in pass rates for Scottish pupils amid Covid disruption. The Herald. https://www.heraldscotland.com/politics/19502772.sqa-results-drop-pass-rates-scottish-pupils-amid-covid-disruption/
Lewis, J. and Bolton, P. (2022) UK Parliament Research Briefing: A levels, Scottish Highers, and university admissions 2022. https://commonslibrary.parliament.uk/research-briefings/cbp-9604/
NIFDI (2024) Project Follow Through. https://nifdi.org/what-is-di/project-follow-through/
Paterson, L. (2026) Lessons from Scottish Schools. Edinburgh: Edinburgh University Press.
Scottish Government (no date) What are the National Standardised Assessments for Scotland (NSA)? https://standardisedassessment.gov.scot/
Stenhouse, L. (1975) An Introduction to Curriculum Research and Development. Oxford: Heinemann.
Surma, T. et al. (2025) Developing Curriculum for Deep Thinking: The Knowledge Revival. Springer. https://link.springer.com/book/10.1007/978-3-031-74661-1.
Thomson, W. (1889) Electrical Units of Measurement, Popular Lectures and Addresses, Vol. 1, pp. 73-4. https://archive.org/details/popularlecturesa01kelvuoft/page/72/mode/2up
Wiliam, D. (2018) https://x.com/dylanwiliam/status/1062144139993776128
Willingham, D. T. (2009) Why Don’t Students Like School? San Francisco: Jossey-Bass.
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