Assessing Big Ideas: Why ACJ Belongs with UbD

Understanding by Design® has had such lasting influence because it starts in the right place. Instead of treating curriculum as a march through content, it asks what learners should understand deeply enough to explain, apply, and transfer. That shift has helped schools design learning that is more purposeful, more coherent, and more authentic.

It also raises the bar for assessment. If the goal is deep understanding rather than surface recall, then the evidence we ask students to produce has to be rich enough to reveal that understanding. In UbD terms, Stage 2 is not a technical afterthought; it is central to the integrity of the whole design.

That is where many schools encounter a familiar tension. UbD encourages teachers to design authentic performance tasks: essays, presentations, podcasts, investigations, portfolios, prototypes, and other complex responses that make big ideas visible. But when that work has to be judged, the system often falls back on tools and habits better suited to narrower, more standardised forms of assessment.

The assessment gap

This creates what might be called the UbD assessment gap: the gap between the richness of the task and the narrowness of the scoring method used to evaluate it.

Rubrics can be extremely useful. They can clarify expectations, support feedback, and give teachers and learners a shared language for quality. But the more open, multi-modal, and conceptually rich a task becomes, the more strain it puts on a conventional analytic rubric.

A single rubric may work reasonably well when student outputs are tightly controlled. It becomes much harder to use fairly when one student responds through a documentary, another through an essay, and another through a digital portfolio. The risk is not just inconsistency. The deeper problem is that teachers can end up judging the visible format of the response, or the checklist items they can easily defend, rather than the quality of understanding itself.

Depth of insight, perspective, empathy, and conceptual transfer all matter. Yet when rubric descriptors become too broad, they offer little real guidance; when they become too detailed, they risk fragmenting the performance into a compliance checklist.

The result is familiar in many schools. Teachers spend more and more time refining descriptors, justifying scores, and moderating edge cases. Students learn to perform to the rubric rather than fully engage with the idea. And a task designed to reveal authentic understanding is judged through a process that often struggles to honour the work as a whole.

A more natural fit

If backward design asks teachers to think carefully about evidence, it is worth asking what kind of judgement process is best suited to complex evidence. This is where Adaptive Comparative Judgement, or ACJ, becomes a compelling partner for UbD. ACJ is a holistic assessment approach in which judges compare two pieces of student work and decide which better demonstrates the intended quality or understanding. Across multiple pairwise comparisons, a reliable rank order can emerge.

That matters because comparison is often a more natural professional act than assigning an absolute score to a complex artefact. Teachers may find it difficult to place rich work cleanly onto a fixed scale, but they are often much more consistent when asked to compare two responses side by side and decide which is stronger overall. Research on ACJ has highlighted the usefulness of this pairwise logic for judging complex outputs holistically.

In other words, ACJ operates at the same level of complexity as the tasks UbD encourages. It allows teachers to judge the artefact in the round, while still focusing on the conceptual purpose of the task. Instead of forcing professional judgement to be broken down into ever finer descriptors before it can count, ACJ gives that judgement a structure that is both disciplined and usable.

Why ACJ belongs with UbD

The strongest case for ACJ is not that it replaces good curriculum design. It is that it completes it. UbD helps teachers design for understanding; ACJ offers a way to judge the resulting evidence that is more aligned with the spirit of that design.

• It respects multi-modal evidence. When different students respond in different formats, ACJ enables judges to focus on the quality of understanding shown rather than forcing every response into the same presentational mould.
• It supports holistic judgement. Big ideas are rarely demonstrated through isolated sub-skills alone. ACJ allows teachers to judge the overall strength, depth, and coherence of a response in relation to the intended understanding.
• It turns moderation into professional learning. Because multiple teachers participate in repeated comparisons, the process helps surface tacit knowledge about what quality looks like. Moderation becomes less about compliance and more about building shared understanding.
• It produces rich exemplars. The outcome is not just a mark or band. It is an ordered set of real student responses that can become a powerful library of exemplars for future planning, feedback, and discussion.

This is especially important for schools and systems trying to create shared standards around authentic performance. UbD gives educators a strong front end for planning. ACJ offers a stronger back end for judging the evidence that authentic planning produces.

Completing the loop

Authentic curriculum design is not the problem. In many ways, it is the solution. The difficulty comes when authentic tasks meet assessment methods designed for narrower, more standardised evidence.

That does not mean rubrics have no place. They remain valuable in many contexts, especially for clarifying expectations and supporting feedback. But when the aim is to judge complex, open-ended work that reveals deep understanding, schools may need an additional assessment approach that better matches the ambition of the task.

That is why Adaptive Comparative Judgement belongs with UbD. It aligns with the same educational instinct: that learning should be judged in ways that respect meaning, complexity, and professional expertise. If schools want students to grapple with big ideas, the evidence of that learning needs to be judged by methods capable of recognising quality in the round.

UbD changed how many educators think about curriculum. The next step is to ensure assessment is equally worthy of that vision.

Understanding by Design® and UbD® are registered trademarks of ASCD. This article is an independent commentary on the framework and is not affiliated with or endorsed by ASCD, Grant Wiggins, or Jay McTighe