Why Vocabulary Matters

By Timothy Rasinski, Ph.D., Professor of Literacy Education, Kent State University

Consider the following sentences:

  1. Tim assumed that Larry was mendacious.
  2. Jerry was surprised to see his colleagues arrogate authorship for the article.

Did you understand them? It’s possible that you had some difficulty. What’s the trouble? The sentence structure for #1 is simple and all the words are decodable. If you had any difficulty with comprehension, it was probably due to a word with which you may not be familiar: mendacious. Mendacious means lying or being dishonest. Now the sentence should be easily understood.

Similarly, in sentence #2 the words are decodable. Although the sentence structure is slightly more complex than #1, it’s still conventional. The potential problem here is another word with which you may not be familiar: arrogate. Knowing that arrogate means “to claim without justification” makes the sentence completely comprehensible: Jerry was surprised to find out that his friends were claiming credit for an accomplishment to which they were not entitled.

Vocabulary matters because readers can’t fully understand texts without knowing the meaning of the words within the text. In other words, textual meaning is constructed on building blocks of vocabulary. Research has consistently demonstrated that vocabulary (knowledge of word meanings) is strongly related to reading comprehension (Anderson & Freebody, 1981). The more words a reader knows, the greater the likelihood that the reader will understand a text.

Moreover, vocabulary knowledge is important right from the start. Cunningham and Stanovich (1997) report that vocabulary knowledge in grade one predicts middle and high school reading achievement.

But just how many words does a reader need to know? Graves (2016) suggests that from the beginning of first grade to the end of high school, a linguistically advantaged student should add about 40,000 words to his or her oral and reading vocabularies. That means this student needs to acquire about 3,300 new words each year, or slightly more than 90 words per week (throughout a 36-week school year).

New Words

It’s true that many of the words students acquire are learned incidentally and informally; but obviously, according to these numbers, the traditional 20-words-per-week vocabulary protocol won’t be adequate for teaching students the words they need to learn before they graduate.

Linguistically less-advantaged students acquire about half that total number of words (still twice the number traditionally taught per school week) which suggests that the reading difficulties experienced by many students are due to their limited vocabularies.

Add to this the fact that various disciplinary content areas contain their own sets of peculiar words reflecting concepts specific to the discipline. Math, science, social studies, art, and many other subject areas feature their own special terms. Not understanding these words results in reduced understanding in these areas.

Then add the fact that all languages, including the English language, are like living entities, in that they are continually growing and changing. Editors of the Oxford English dictionary estimate that they add approximately 1,000 new entries to the dictionary each year. More words means there are more words that need to be learned.

Despite the fact that many words are learned simply through life’s experience, the need for intentional school-based vocabulary instruction is more important than ever. Blachowicz et al. (2006) recommend that teachers make vocabulary a core instructional consideration coordinated within and across grade levels.

Just what might that vocabulary curriculum look like and what might be included in that curriculum? In my next Guest Author post for the Learning A-Z Breakroom, I will explore how we might make vocabulary instruction more effective for all students, and in doing so, improve students’ reading outcomes.


Anderson, R., & Freebody, P. (1981). Vocabulary knowledge. In. J. Guthrie (Ed.). Comprehension and teaching: Research reviews (pp. 77-117). Newark, DE: International Reading Association.

Blachowicz, C., Fisher, P., Ogle, D., & Watts-Taffe, S. (2006). Vocabulary: Questions from the classroom. Reading Research Quarterly, 41, 524-539.

Graves, M. (2016). The vocabulary book: Learning and instruction (2nd ed). New York, NY: Teachers College Press.

A Cambium Learning Group Brand

A Cambium Learning® Group Brand