What is knowledge architecture?

And why is it important in assessment design?

When creating assessments, our aim extends beyond merely evaluating whether students have grasped the current curriculum. We also engage in forming value judgements about varying types of knowledge deficits among students, as these judgements significantly influence the construction of our assessments.

For instance, consider two students, Dylan and Freddie, both lacking in certain mathematical concepts that should have been acquired during Key Stage 2. Dylan is unfamiliar with Roman Numerals, whereas Freddie struggles with fractions. To a maths teacher - and arguably, to society at large - Freddie's deficit is far more concerning for reasons related to the structure of knowledge within mathematics. Such insights are invaluable when deciding what to include in assessments and how to weigh each component.

In this post, we turn our attention to examining the structure of knowledge within your subject. Knowledge isn't just an isolated set of facts; it comprises interconnected pieces of information. However, the nature and complexity of these connections can differ substantially across subjects, thereby influencing how we approach assessment. We refer to the way in which this knowledge is organised as its knowledge architecture. This architecture serves as the blueprint for the conceptual schema we aim to cultivate in our students.

While 100% Assessment is not about curriculum design, we aim to offer a simplified yet sufficient understanding of your subject's knowledge architecture for the purpose of crafting appropriate assessments. Specifically, we'll explore whether the knowledge structure in your subject is hierarchical, marked by strict dependencies among concepts, or whether it adopts a flatter, more flexible configuration.

Hierarchical versus Cumulative Knowledge Architecture Within a Curriculum

Let’s begin by defining our terms. In a hierarchical knowledge architecture, certain foundational concepts must be fully understood before one can progress to more advanced topics. Conversely, a cumulative knowledge architecture allows for a more flexible accumulation of knowledge, where understanding one concept doesn't necessarily depend on mastering another.

In a hierarchical architecture, each layer of knowledge builds directly upon the previous one; think of it as a pyramid of understanding. In a cumulative architecture, the knowledge structure might be more akin to a web or the exploration of a landscape, where various strands of understanding can be developed somewhat independently.

Mathematics is a classic example of a hierarchical subject; you can't tackle calculus without a solid grasp of algebra, which leads to a more rigid, sequential curriculum. Other subjects have strong hierarchical features: Science has many hierarchical dependencies between concepts; the grammatical elements of modern language are hierarchical and thus need to be introduced in careful order; ball skills in PE and pencil/paint skills within art have these dependencies.

History, on the other hand, may be more cumulative; understanding the Cold War doesn't require detailed knowledge of Ancient Rome and so schools might vary in when or if each topic is taught. Most humanities and social science teachers (except economists) will relate to these cumulative features, as will those teaching literary and creative subjects.

Many subjects have both hierarchical and cumulative elements, with the degree of curriculum agreement and latitude in teaching may varying. For instance, English becomes less hierarchical and more cumulative as it progresses from teaching reading, grammar, and spelling to exploring literary texts. Music theory is the hierarchical grammar of the subject, whereas the study of musical works and composition is cumulative. Carpentry skills in design and technology are hierarchical, but there is significant latitude in how lesson time is used to explore the use of these basic skills. Even a generally agreed hierarchical subject like science has exploratory topics within the curriculum, such as the environment or recycling.

Why does knowledge architecture matter?

The type of knowledge architecture impacts how we design assessments. Hierarchical subjects necessitate a rigorous and repeated testing of foundational knowledge, as a deficit here could be detrimental to understanding the subject as a whole. Cumulative subjects often allow for assessments that offer multiple avenues for demonstrating competence. Understanding the architecture is also crucial for making value judgements about what to include in assessments. For instance, gaps in foundational knowledge in hierarchical subjects are generally more concerning and therefore require remedial efforts.

It's worth noting that even when there's a clear and consistent consensus within a subject community about its knowledge architecture, we can't definitively determine how students cognitively engage with that subject. For instance, we lack concrete data on the differences in neural activity between students studying hierarchical versus cumulative subjects. Nor can we ascertain whether students in hierarchical subjects with well-defined architectures engage more consistently with ideas than those in other subjects. In the end, our understanding of knowledge architecture is rooted more in collective belief than in empirical certainty.

The Interplay Between Knowledge Structure and Assessment Openness

We can think of assessment tasks in terms of their ‘openness’, meaning the extent to which a task allows for varied responses. The nature of this openness is intimately tied to the structure of the subject's knowledge domain - whether it is hierarchical or cumulative. Hierarchical subjects, with their layers of prerequisite knowledge, often use more closed forms of assessment, like multiple-choice questions or short answers, to pinpoint and repeatedly check whether students have grasped foundational elements. In contrast, cumulative subjects, where concepts are more interrelated than sequential, are amenable to open tasks like essays, projects, or presentations, which allow students to demonstrate a breadth of understanding.

Closed tasks have the advantage of being straightforward to grade and offer a clear metric for foundational knowledge. However, they might not capture the depth or nuance of understanding, especially in cumulative subjects where links between key ideas might be fuzzy or far-reaching. Of course, the relationship between knowledge structures and assessment openness is not tightly defined and there are many influences on choice of assessment task (including public examination task choices). Within subjects with cumulative knowledge structures overall, we often use closed tasks extensively during the learning process to test recall of individual ideas, before moving to more open tasks once key ideas are secure.

In some subjects, it is important to us that students’ knowledge is precise and specific. For example, in Chemistry, we may deem it important that students know how the elements in the periodic table are organised. We may believe that you cannot be a competent Chemistry student without knowing this and that this knowledge is fundamental to more advanced understanding of the subject. These beliefs arise to some extent from the hierarchical knowledge architecture of the subject and the fact that this knowledge is uncontested within the discipline. It is legitimate in Chemistry, therefore, to tend towards asking somewhat closed questions to assess whether students have the required knowledge.

In contrast, for the study of poetry in English Language, knowledge of a specific poem may be less important than the students’ ability to recognise poetic devices and compare their effect across selected pieces. Whether students’ knowledge relates to First World War poetry, or the romantic poets may matter less than their analysis of the chosen work. We know that what constitutes valued knowledge in the study of English Language is less well defined and more contested than in the sciences. The subject also has a flat structure with horizontal links between domains of knowledge meaning that understanding of one domain is not contingent on understanding in another. For this subject, we are drawn towards comparatively open questions which permit the student to draw on a broad body of knowledge to construct their response. The novelty (i.e. the variety and uniqueness) of each student’s response is valued above the precise recall of particular knowledge.

So, that is why knowledge architecture is an important factor when it comes to designing assessments.