We talked of the difference between the mode of education at Oxford, and that in those Colleges where instruction is chiefly conveyed by lectures. JOHNSON: ‘Lectures were once useful; but now, when all can read, and books are so numerous, lectures are unnecessary. If your attention fails, and you miss a part of a lecture, it is lost; you cannot go back as you do upon a book.’
Boswell’s Life of Samuel Johnson

The root of the term ‘exposition’ is ‘a setting forth’ (e.g., Expo ’98 etc.). Although the best anchor for recognising what this term means is the university lecture: an episode in which someone stands up and ‘sets forth’ what is known. It is intriguing that lectures flourish today – amid an abundance of books – when they could be deemed “unnecessary” even in the eighteenth century. Of course, books are also expository. Knowledge is set forth for us, but in text, rather than by voice. So, Dr Johnson’s unease is not with exposition per se, but with lecturing as a now-redundant way of doing it. And he goes further. In making the lecture/book contrast, he identifies an important form of learner agency that characterises certain expository forms but is denied by others. He notes that the expository book (and we might add lecture video) affords engaging with the text through an action of “going back” (or forward, or simply pausing). That is to say, in certain cases the learner can exercise control over how they process someone’s ‘setting forth’. In short, the possibility of a relationship is on offer in exposition. Freedom in pacing and navigating a text is one realisation of this relationship.  But there are other ways in which a learner can be a participant in expository formats. Identifying these is a central purpose of the present chapter.   

The pros and cons of the university lecture will not be re-visited here (but see, for example, Barnett, 2000; Bligh, 1971; Crook, 2024; Laurillard, 2002). Yet it will prove useful to address a more wide-ranging controversy around exposition: one that is often debated under the heading ‘direct instruction’. That debate concerns whether or when knowledge should be ‘set forth’ as expository instruction – as opposed to it being ‘called forth’ as discovery. The latter implies a responsibility for the learner to find what is known, rather than them being “directly” told what is known. Where that tension has been vigorously debated is in relation to the learning of concepts that are significantly challenging – particularly (but not exclusively), concepts that are central to science, technology, engineering, and mathematics (‘STEM’ subjects). In the first section below, we consider what it is about such ‘conceptual knowledge’ that makes it so “challenging”. But also, whether expository learning may be an important route towards achieving that knowledge.  Later in the chapter, the processes of exposition (i.e., psychological ‘workings’) will be explored so as to understand it as another act of learning.  What that involves, as with other topics in this book, is considering how the learner effectively takes part in this learning practice. Specifically, how the learner acts to optimise their relationship with an exposition. We shall identify three attentional dispositions that learners can bring to this relationship: engagement, immersion and distraction.