The Missing Half of Reading: Why Science Texts Need Knowledge, Not Just Strategies

Consider a pupil facing a GCSE question: explain how a vaccine produces immunity. The pupil can read every word. They may know that explain means give reasons. They may have been taught to underline the command word and write three points. Yet if they do not know what a vaccine contains, what an immune response is, or how antibodies relate to pathogens, the question is not really a reading task at all. It is a knowledge task wearing the clothes of a reading task.

This is the central problem in much discussion of reading in science. Strategies matter, and decoding matters, but neither can supply the domain knowledge that a science text assumes. Background knowledge is not a luxury for the most able; it is part of what comprehension is.

The comforting idea that reading more will fix reading

Reading more is usually good advice. But it is not a neutral remedy. A pupil who reads widely may build general knowledge, but science texts assume specialised knowledge that general reading does not reliably provide. A novel may build empathy and narrative understanding; it will not necessarily explain limiting factors in photosynthesis or why a filament lamp does not obey Ohm's law.

The phrase reading more also hides a problem of selection. Pupils who already have richer knowledge tend to read more, and to read more demanding texts. Pupils who struggle with science texts may avoid them. Simply increasing the volume of reading, without attention to what is being read and what knowledge it assumes, can widen rather than close gaps.

What background knowledge does in a science sentence

Take a sentence such as: the enzyme is denatured at high temperature. The word denatured is not a word whose meaning can be reliably inferred from the surrounding sentence. It points to a model of protein structure and active sites. A pupil who has that model can infer why the rate of reaction falls. A pupil who does not has to guess.

Or consider: the current-voltage graph is not a straight line. To explain this, a pupil needs more than graph-reading skill. They need to know about resistance, temperature and the behaviour of a filament lamp. In primary science, evaporation and boiling may be used almost interchangeably in everyday speech, but the science text depends on a distinction. Knowledge includes concepts, examples, procedures and the conventions of scientific writing.

Strategies are useful, but they are not the curriculum

Comprehension strategies such as predicting, questioning, clarifying and summarising help pupils monitor their reading. They are general tools, and they are worth teaching. But they do not tell a pupil what equilibrium means, why a control group matters, or how to interpret a table of results.

An overemphasis on generic skills can be particularly unhelpful for pupils with less prior knowledge. Strategies are easier to apply when you already understand the content. This is not an argument against reading instruction. Decoding and fluency matter, and vocabulary matters. But science departments cannot delegate comprehension to English. Disciplinary literacy means teaching pupils how to read the texts of a subject, and that includes the knowledge those texts assume.

What exam-style questions expose

UK exam questions often combine command words with content, and the combination is revealing. A question may ask pupils to explain the trend shown in a graph of light intensity and photosynthesis. The pupil needs to read the graph, but also to know about limiting factors. A question may ask why a student's results were not valid. The word valid is not a strategy; it signals ideas about variables, control and measurement.

Another question may ask pupils to use the particle model to explain why pressure increases. Teaching command words as templates is not enough. Suggest invites a reasoned link between evidence and theory; without theory there is nothing to link. Explain requires a causal account, not a list of disconnected points.

Knowledge and reading as partners

Science departments should treat knowledge-building and reading instruction as partners rather than competitors. That has practical implications. Teachers can choose texts that extend pupils' knowledge rather than merely decorate it. They can pre-teach essential concepts, use retrieval practice, ask inference questions, build vocabulary in context, and pair diagrams with prose.

Curriculum sequencing matters too. Primary teachers build world knowledge through science topics, and that knowledge supports later reading. Lower-secondary teachers make disciplinary vocabulary explicit and show pupils how explanations are structured. None of this is separate from subject teaching; it is part of it.

A curriculum that reads

Every teacher a teacher of reading can become a slogan. A more precise claim is that every subject teacher teaches pupils to read the texts of that subject. That requires time, suitable texts and training. Knowledge organisers are useful, but they are not substitutes for prose. Short texts can be used, and assessment should ask pupils to explain, not merely recall.

The choice is not between knowledge and reading. Science reading demands both. If we treat background knowledge as a luxury, we make comprehension a test of what pupils have already had the chance to learn. If we treat strategies as sufficient, we hand pupils a toolkit and no materials. The more defensible position is partnership: teach the knowledge, teach the reading, and do not pretend that one can stand in for the other.