Saturday / June 22

Revisiting Inside the Black Box 20 Years On

Just over 20 years ago, two British researchers, Paul Black and Dylan Wiliam, published their famous review on formative assessment: Inside the Black Box. Black and Wiliam’s extensive review concluded that formative assessment was a game changer; implemeting this type of assessment could lead to significant learning gains for students (Black and Wiliam, 1998a). Their review stimulated worldwide interest, resulting in formative assessment being taken up in countries from the US to Pakistan to Ethiopia.

Black and Wiliam (1998a) defined formative assessment as:

encompassing all those activities undertaken by teachers, and/or by students, which provide information to be used as feedback to modify the teaching and learning activities in which they are engaged (p.7).

This definition made clear that formative assessment is not a specific kind of test. Rather, formative assessment is a process that entails seeking evidence of the ways in which students are developing their knowledge, skills, and understanding with the intention of using the evidence to inform student learning, minute by minute, day by day. Assessment opportunities are embedded into the ongoing learning activities and interactions in the classroom and the evidence generated is used by both teacher and students to move learning forward (Heritage & Harrison, 2019).

Black and Wiliam’s review also made clear that implementing formative assessment will likely require changes in how teachers do business in their classrooms:

It is hard to see how any innovation in formative assessment can be treated as a marginal change in classroom work. All such work involves some degree of feedback between those taught and the teacher, and this is entailed in the quality of their interactions which is at the heart of pedagogy (Black & Wiliam, 1998b, p. 16).

We have certainly found this to be the case in our own work.

Consider this reflection by Shawn, a middle school teacher, on the significant changes that occurred in his classroom as a result of implementing formative assessment:

I used to do a lot of explaining, but now I do a lot of questioning.

I used to do a lot of talking, but now I do a lot of listening.

I used to think about teaching the curriculum, but now I think about teaching the students (Heritage & Harrison, 2019, p. 89).

From Shawn’s reflection, it’s possible to imagine the kind of changes he made to his practice, and they are certainly not marginal. He now obtains evidence from questioning and listening to students’ responses and discussions, and uses the evidence to advance the learning of each student. It’s as though he turned 180 degrees in his classroom practice to fully embed formative assessment into teaching and learning.

Making the kinds of transformations that Shawn described is not a simple fix. Teachers who take up formative assessment as an integral part of their classroom practice do not quickly go from zero to perfection.

One catalyst advocated by Black and Wiliam to set these transformations into motion is for teachers to engage in “scrutiny” of the teaching plan. This “scrutiny” is motivated by a belief that the transmission model of learning is not the most effective one, and by a commitment to teach through interaction—“the heart of pedagogy” according to Black and Wiliam. “Scrutiny” includes considering the nature of learning tasks, of classroom questioning and discussions, and of opportunities for students to explain their thinking as a means both to learn and provide evidence of learning. Shawn engaged in “scrutiny” of his teaching plan and made significant changes. Many other teachers have been willing and able to do the same.

As one 4th Grade teacher stated:

My planning has changed a lot. Instead of being focused on the activity and what I am going to say, I’m focusing on what are the students learning and what are they doing with the learning, and then me thinking through what they might not understand and how could I question in a way to help push them towards understanding, as opposed to me presenting information and students passively consuming it (Heritage & Harrison, 2019, p. 69).

This teacher goes on to say that she has seen some “great things in her classroom” but acknowledges that the changes are sometimes out of her “comfort zone in a productive struggle sort of way.” Nonetheless, she is a strong advocate for formative assessment and is determined to make it a seamless part of teaching and learning in her classroom.

While the practices that we now identify as formative assessment have always been within the repertoire of good teachers, the process of actively seeking evidence of learning and intentionally using that evidence to make decisions about next steps has only really come to the fore since Inside the Black Box was published. In the subsequent 20 years, formative assessment has become a deep-seated practice in many classrooms in many countries.

We do not have a crystal ball, but we are willing to bet the formative assessment will continue to be a mainstay of classrooms for the next 20 years, and as we have more evidence of classroom teachers’ implementation we will see it develop in new and fruitful directions that benefit students across the world.


Black, P., & Wiliam, D. (1998a). Inside the black box: Raising standards through classroom assessment.  Phi Delta Kappan, 80(2), 139-148.

Black, P. J., & Wiliam, D. (1998b). Assessment and classroom learning. Assessment in Education: Principles Policy and Practice, 5(1), 7-73.

Heritage, M., & Harrison, C. (2019). The power of assessment for learning: Twenty years of impact in UK and US classrooms. Thousand Oaks, CA: Corwin.

Written by

Margaret Heritage is an independent consultant in education. For her entire career, her work has spanned both research and practice. In addition to spending many years in her native England as a practitioner, a university teacher, and an inspector of schools, she had an extensive period at UCLA, first as principal of the laboratory school of the Graduate School of Education and Information Students and then as an Assistant Director at the National Center for Research on Evaluation, Standards and Student Testing (CRESST) UCLA. She has also taught courses in the Departments of Education at UCLA and Stanford. Christine Harrison is a Professor in Science Education at King’s College London, where she works as a researcher and teacher educator. Chris’s career began in schools and developed through curriculum development projects and examining in the U.K. before she began working on her own research. Working at a prestigious university, and also spending considerable time in classrooms on research and supporting pre-service teachers, Chris began to realize that there was a gap between research ideas and practice. To that end, she has worked with many teachers, researchers and organizations helping all learn from practice-based evidence so they can understand how practice across a variety of contexts centers around the principles of the research. Her work is published in peer-reviewed journals, edited books, and practitioner journals, and she has produced several on-line courses for teachers and researchers. Chris is Associate Director (London) for the Centre for Innovation in Teacher Education and Development, w a joint institutional strategic initiative between Teachers College, Columbia University and King’s College London, committed to the principles of equity and social justice. She is also a leading STEM educationalist in Europe working at research, practice and policy level.

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  • Black & Wiliam are inspiring. I am reading their articles of indepth analysis now.

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