By Paul Black and Dylan Wiliam

The impact of “Inside the Black Box” has been a pleasant surprise. As we reflect over 10 years later, this success raises two questions: Why has it been so well received, and what’s the nature of its influence, both on the development of thinking about the concept of formative assessment and on the professional work of teachers?

We think two main factors led to the positive reception of the article. The first was its grounding in evidence — our extensive review of research evidence showed that formative assessment innovations could improve the attainments of learners at all levels of education. We shared evidence that few teachers were using such approaches. The second was that we went beyond the evidence to propose how teaching should change to make assessment more effective. This drew on our experience as school and college teachers and took advantage of our — often implicit — knowledge about teacher education, about innovations in curriculum and pedagogy (at both school and college level), and about large-scale summative assessment.

Much has happened since publication in 1998 to develop the concept of formative feedback. We have learned more clearly that interactive dialogue, between teacher and learners and between learners themselves, is at the heart of formative practice and that such practice should enrich the central task of teachers. That task is to engineer learning opportunities so that learners can become more expert and more responsible in guiding and furthering their own learning (Black and Wiliam 2009).

If we were to rewrite this article now, we’d highlight this strategic principle at the outset and make clear that the activities we discussed were means to this end. Our experience of the practical impact, particularly through our own work with schools and districts, has shown that this overview is lacking for many, formative assessment being seen merely as a collection of extra ideas to add to a teacher’s arsenal. For us, it’s far more radical and requires many teachers to fundamentally change how they relate to students, to become better listeners themselves, and to learn to promote, respect, encourage, and build on student contributions. Such change requires courage and calls for mutual support between teacher colleagues in sustained, in-school professional development (Wiliam 2007/2008).

It also requires returning to the research evidence to examine critically how much benefit different kinds of formative assessment are likely to have. Banks of “formative assessments” may have a role in highlighting poor alignment between instruction, curriculum, and assessment. However, in most cases, using assessment during instruction, as a way to improve the evidence on which teachers’ “on-the-fly” instructional decisions are based, will have a far more significant impact on student achievement.


Black, Paul J., and Dylan Wiliam. “Developing the Theory of Formative Assessment.” Educational Assessment, Evaluation, and Accountability 21, no. 1 (2009): 5-31.

Wiliam, Dylan. “Changing Classroom Practice.” Educational Leadership 65, no. 4 (December 2007/January 2008): 36-42.

Author information.
PAUL BLACK is emeritus professor of science education at King’s College London, United Kingdom. DYLAN WILIAM is deputy director of the Institute of Education, University of London, United Kingdom.

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Originally published in the September 2010 Phi Delta Kappan 92 (1), 47-48.  © 2010 Phi Delta Kappa International. All rights reserved.

Inside the Black Box: Raising Standards Through Classroom Assessment