Five Words a Day: What Research Says About Building Children's Vocabulary

Most of us learned vocabulary the way we learned most things in school — by looking up definitions and writing sentences. But researchers have known for a while that this approach doesn't stick very well. What does work? Hearing and using rich, interesting words repeatedly, in context, over time.

Recent research continues to confirm something encouraging: you don't need to overhaul your whole routine to make a real difference. Small, consistent vocabulary habits — even just a handful of words a week — can meaningfully improve a child's reading comprehension.

What Researchers Found

A growing body of evidence supports what literacy researchers call "rich vocabulary instruction" — a method where teachers (and parents) don't just define a word once, but introduce it in multiple contexts, connect it to things children already know, and revisit it across days and weeks.

Studies from the past several years, including work reviewed by the What Works Clearinghouse and researchers at Florida State University, show that children who receive this kind of intentional word instruction outperform peers on both vocabulary assessments and reading comprehension tests. The connection makes sense: if you don't know what words mean, it's very hard to understand what you're reading, even if you can decode every single word on the page.

One particularly useful finding is that Tier 2 words — words that appear across many subjects and texts, like analyze, reluctant, enormous, or predict — give children the most return on investment. These aren't everyday words, but they're not highly technical either. They show up in books, in school, and in conversation, and knowing them opens doors.

Why It Matters

Vocabulary is one of the strongest predictors of reading comprehension, and the gap between children with rich word knowledge and those without tends to grow over time — not shrink. Children who enter school with smaller vocabularies often struggle to catch up without intentional support.

The good news: vocabulary is highly teachable. Unlike some aspects of reading that require specialized instruction, building word knowledge is something every caring adult can do.

What You Can Try

For parents: When you're reading together and come across an interesting or unfamiliar word, pause and talk about it. Don't just define it — use it in a sentence from real life, ask your child if they've heard it before, and try to use it again later that day. ("Remember that word reluctant from the book? You were a little reluctant to eat your broccoli tonight!") Repetition in context is the key.

For teachers: Choose 3–5 Tier 2 words per week tied to your read-alouds or content units. Introduce them with a brief, kid-friendly definition, show them in context, and build in quick review activities across the week — a quick "thumbs up if this sentence uses the word correctly" check takes 60 seconds and does real work.

Small, steady effort adds up. A few well-chosen words, revisited often, can make a lasting difference.

Sources

• What Works Clearinghouse, Vocabulary Instruction Practice Guide, U.S. Department of Education, 2022
• Beck, I.L., McKeown, M.G., & Kucan, L., Bringing Words to Life: Robust Vocabulary Instruction, Guilford Press (3rd ed., 2023 update)
• Florida State University Reading Research Center, research summaries on Tier 2 vocabulary instruction, 2024
• Reading Rockets, "Vocabulary," readingrockets.org, accessed 2026