Background Knowledge and Reading Comprehension: What Studies Found

By Laura Lurns · Reviewed by Philip Weaver · Last reviewed 2026-10-20

Why knowing the subject matters

Understanding what you read depends on at least three things. The reading has to be smooth enough to leave room. The child has to know the words. And they have to know enough about the subject for the sentence to mean something.

A 1986 model of reading names two parts (Gough and Tunmer, 1986). One is reading the words. The other is understanding the language. A child can do the first well and still not understand. It is a model, not a study.

In our view, talking about a topic first gives the words something to attach to.

What studies of readers found

One study sorted 64 junior high students two ways (Recht and Leslie, 1988). One was how well they read. The other was how much they knew about baseball. Then the students read about half an inning of a game.

The students who knew more about baseball recalled more, on every measure. The benefit from knowing more did not depend on how well they read. We could read only the study's summary.

A 2021 review looked at 23 studies on understanding what you read (Smith and colleagues, 2021). The children were in the middle and later years of primary school. What knowing the topic did depended on the text. It also depended on wrong ideas the reader already held.

The review said weaker readers "were able to compensate somewhat" when they knew a lot. That means knowing the topic made up a little for weaker reading. We could read only the review's summary.

What happened when schools taught knowledge on purpose

One trial took place in 38 first-grade classrooms in 10 schools (Kim and colleagues, 2021). By chance, some classrooms taught a 10-day science unit built around one theme. The rest kept their usual lessons.

The unit helped the children's science knowledge. It helped them understand what they heard, and write an argument. It also helped on one reading test. The summary we hold does not say what that test was about. It did not change how engaged the children were with reading.

In this study, children did not need to be strong already to gain. We could read only the study's summary.

A second trial took place in 30 schools, with 2,952 children (Kim and colleagues, 2023). The schools were split by chance. Some children had science and social studies lessons built around themes. This ran through first and second grade.

Those children lost less reading over the summer, on a general reading test. The summary we hold does not say what that test's passages were about. The children also understood new science texts better. We could read only the study's summary.

These were classroom lessons, not talk at home. Those findings are about groups of children, not a promise about yours.

A school study that is not yet peer-reviewed

A third school study is a working paper, not yet peer-reviewed. Other researchers have not checked it yet.

It looked at nine Core Knowledge charter schools (Grissmer and colleagues, 2023). These schools had more children apply than they had places. So a lottery picked who got in, by chance. There were 14 lotteries for kindergarten places, and 2,310 children applied. Most came from middle- and high-income districts.

Children who won a place scored higher on state reading tests than those who did not. That was in grades 3 to 6.

The lessons came bundled with the school. So the study cannot tell the school apart from what it taught. We could read only the paper's summary.

What these studies do not show

The studies we hold do not show help with reading on an unrelated topic. In the 2023 trial, the gain shrank as texts moved away from what was taught.

No study of background knowledge we hold picked children because they had trouble reading.

We hold no study of building knowledge at home. That is a gap in what we hold, not a finding either way.

Building knowledge is not training memory as a skill. What carries over is the knowledge itself, in texts that use it.

None of these studies looked at any Learning Success program.

Building knowledge at home

This part is our suggestion.

Talk about the topic first. Ask what your child already knows about the topic. In our view, a book on a new subject is harder to follow. Add one or two facts of your own.

Stay on one topic for a while. Our suggestion is to read a few books on one topic in a row. The same words and ideas keep coming back.

Audiobooks. In our view, audiobooks are not cheating. Use them alongside reading instruction, not in place of it.

That routine is ours. We hold no study of it at home.

When to ask for help

Each of these is a reason to ask for help on its own.

• Little change, even with steady practice and good teaching.
• Reading well below what school expects.
• A teacher who raises a concern about reading.
• Extreme upset about reading.
• Complete avoidance of reading.
• Hopelessness about learning.
• Sadness or worry that lasts.
• Significant delays in speech, language or motor development.
• A skill that was there and has gone. Our position is that a lost skill goes to a doctor first, not a tutor.

If no skill has gone, start with the teacher. Say what you are seeing at home, and what you have tried. Beyond the teacher, the right person depends on what it turns out to be about. If the work is too hard, someone who works on that school skill. If worry or mood is the thing, someone who works with children's mental health. In our view, delays in speech, language or movement are worth raising with your child's doctor. In our view, if you are worried enough to ask, a professional evaluation is worth asking about.

Any talk of hurting themselves is a same-day call to your doctor or a crisis line.