Why Reading Comprehension Can Stall After Third Grade: The Role of Vocabulary

Around third and fourth grade (Years 4–5 in England), texts become longer and use more unfamiliar words. Some children who coped well in the early years start to find understanding harder. Vocabulary and background knowledge are often a big part of the picture.

From learning to read to reading to learn

In the early years, much reading instruction is about decoding. Later, children increasingly read to learn new information, a shift often linked to Jeanne Chall’s stages of reading development. Texts introduce more subject-specific and less common words, and understanding depends more on vocabulary and background knowledge.

In the 2024 The Nation's Report Card: 2024 Reading Assessment, around three in ten US fourth-graders scored at or above “Proficient” in reading, which shows how many children could benefit from support with comprehension.

Why vocabulary matters so much

It is hard to understand a passage containing many unfamiliar words. Research on vocabulary and reading, including the National Reading Panel: Teaching Children to Read, supports teaching vocabulary both directly and through wide reading. Children also need background knowledge: a text about volcanoes is easier if you already know a little about them.

The Matthew Effect in reading

Psychologist Keith Stanovich (1986) described a “Matthew Effect” in reading: children who read well tend to read more, which builds vocabulary and knowledge, which makes reading easier still. Children who find reading hard may read less, so the gap can widen over time. This is why early, steady support with vocabulary and reading volume is valuable.

Comprehension skills check

What parents can do

• Keep reading aloud books above your child’s reading level.
• Talk about new words and use them again in conversation.
• Encourage non-fiction on topics your child enjoys.
• Ask your child to summarise what they read.
• Practise comprehension strategies such as predicting, questioning and clarifying, as recommended in the Improving Reading Comprehension in Kindergarten Through 3rd Grade practice guide.

Frequently asked questions

Sources and further reading

• The Nation's Report Card: 2024 Reading Assessment (NAEP, grades 4 and 8)
• National Reading Panel: Teaching Children to Read (NICHD, 2000)
• Improving Reading Comprehension in Kindergarten Through 3rd Grade (IES What Works Clearinghouse practice guide)
• National Literacy Trust: support for parents and families