JOHNY DANIEL, ASSOCIATE PROFESSOR, DURHAM UNIVERSITY, UK
Context
How many words students know and how well they know them are central to reading comprehension (Beck et al., 2013). Yet comprehension is not a free-floating skill that transfers across any text; it is dependent on what a reader already knows. In one study (Kaefer et al., 2015), preschoolers who knew less about birds understood a storybook about birds less well than their peers. When the story instead featured an invented creature, unfamiliar to every child, the comprehension gap disappeared. What looked like a difference in reading ability was, at least in part, a difference in prior knowledge. This matters, especially for students with specific learning difficulties such as dyslexia. In a large longitudinal study (Quinn et al., 2020), vocabulary growth did not translate directly into comprehension gains for these students, who started behind their peers and did not catch up. This is a reminder that words must be taught alongside knowledge, and that some students need more intensive, explicit teaching. Because gaps in words and knowledge widen over time (the ‘Matthew effect’; Stanovich, 2009), every teacher, in every subject, can narrow them by explicitly teaching new words while building the topic knowledge that makes those words meaningful.
What do teachers need to know?
The single most useful shift is to treat comprehension as knowledge-dependent rather than generic. Teaching students isolated ‘comprehension skills’ in the abstract does far less than building the conceptual knowledge and vocabulary that lets them make sense of real texts. Vocabulary and knowledge are reciprocal: words are the labels for concepts, and concepts give words something to hold onto. You cannot build one deeply without the other, so the most efficient classroom practice builds them together.
Two evidence-informed strategies
1. Content-rich, sequenced vocabulary and knowledge teaching
Organising explicit vocabulary teaching around coherent topics (e.g. ‘the water cycle’) rather than loose themes (e.g. ‘weather’) lets students meet the same key vocabulary and concepts repeatedly, across several texts, building understanding in depth rather than only in passing (Neuman, 2026). This repetition is what helps knowledge to settle and become a network with which students can reason. A meta-analysis of 35 studies with over 13,000 primary-age students found that teaching literacy through subject content, rather than separately from it, improved both vocabulary and comprehension (Hwang et al., 2022). This approach also creates a shared knowledge base, so that discussion in classrooms is no longer dominated by the few who arrived already knowing the content.
2. Direct and extended vocabulary instruction
Many students, especially those with specific learning difficulties such as dyslexia, do not have access to sophisticated academic vocabulary incidentally. They benefit from words being taught explicitly. Following the sequence set out in Beck et al.’s (2013) robust instruction framework: begin with a clear, student-friendly explanation; introduce the word in meaningful contexts; then use extended activities (examples and non-examples, sentence generation, comparisons) that encourage deeper processing rather than rote memorisation.
One inclusion caveat applies across both strategies: while high-quality whole-class teaching benefits all students, it does not necessarily close gaps on its own. This is because students with stronger vocabulary knowledge are often better positioned to acquire new words more quickly. Some students will therefore require additional, targeted support alongside high-quality classroom instruction.
Action points for teachers
- Plan around topics and recycle taught vocabulary: Choose a topic that can be taught over multiple lessons and identify a small set of ‘big ideas’ that you want students to learn. Sequence several texts on that topic so that keywords recur in different contexts; spaced, repeated encounters do more for retention than a single defined-and-moved-on introduction. If you cannot redesign the whole curriculum, then apply this within your existing units.
- Teach a few words well, and not many words lightly: Select a manageable number of high-value words per topic. For each one, give a simple definition in plain, accessible language, demonstrate its use in a supportive sentence, pair it with an image where possible, and revisit it.
- Anchor abstract words to concrete ones: Start with concrete, imageable nouns that carry the topic (‘clouds’, ‘evaporation’) before leaning on abstract academic verbs (‘compare’, ‘analyse’). An abstract verb like ‘compare’ is empty until students have something concrete to compare, so the nouns come first to give the verbs something on which to work.
- Sequence your questioning from recall to reasoning: Move deliberately from quick recall and closed questions (‘What happens when the sun heats water?’) through understanding (‘Why do clouds form?’) to reasoning (‘How would the water cycle change if there were no mountains?’). The early questions give every child the footing with which to take part in deeper thinking.
- Notice who needs more support, and intensify instruction: Use informal checks, students’ spoken use of target words and written responses to spot students who are not keeping pace. To intensify instruction, provide smaller-group, more frequent, explicit reteaching for them, ideally within your school’s tiered support system. Doing this early counteracts widening gaps rather than waiting for the students to fall behind.
Top tips
- Knowledge is the engine of comprehension. Build it on purpose. Don’t assume that students bring the background that a text needs; teach it so that understanding is available to all, and not just the already advantaged.
- Teach words and knowledge together. Vocabulary taught inside rich content sticks; vocabulary taught as lists drifts away. Let your content carry your words and your words deepen your content.
- Front-loading knowledge is an equity move. Establishing shared knowledge before discussion stops your classroom from simply rewarding the students who walked in already knowing the answer.
Want to know more?
A collection of free, ready-to-use lesson plans can be found at www.readingresourcecentre.org, showing how vocabulary and knowledge-building work together in practice; this is ideal if you want to see the principles in this article turned into classroom-ready sequences you can adapt.
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