Michael L. Kamil on using different vocabulary strategies at different reading levels

The most important finding from the vocabulary research analysis conducted by the National Reading Panel is that explicit teaching of vocabulary improves comprehension. It is also true that students will need and will acquire vocabularies much larger than what can be explicitly taught. Therefore, the words used for explicit instruction must be carefully selected to correspond to what is needed at each reading level.

The role of vocabulary changes as reading proficiency increases and the changing role dictates different criteria for choosing words for explicit instruction. Beginning readers need an oral vocabulary that provides the oral language base for learning to read. Students learn to decode print to speech and use their oral language to comprehend what was decoded. When a student decodes a word, the representation must map onto oral vocabulary if it is to be meaningful. Decoding the print word ‘cat’ into the oral form ‘/k/ /æ/ /t/’ allows the student to interpret the print as a familiar word.

By contrast, any print word that is not in a child’s oral vocabulary results in a meaningless exercise. To illustrate this, suppose a child encountered the print word ‘ferple’ and decoded it appropriately. The oral representation would not allow the child to make the print form more intelligible—it would remain unfamiliar in both print and oral forms.

What this means is that at the early grades, students must have a sufficiently large oral vocabulary that the words they encounter in their readers will be meaningful when decoded. Publishers of educational materials attempt to limit the vocabulary in early readers to those words that students will likely know.

Students must have the oral vocabulary that appears in the materials they use for learning to read. A list like that of Biemiller’s Tiered Words in "Small Kids, Big Words: Research-based strategies for building vocabulary from preK to grade 3" (HEL, May/June 2008), is an important source of those words as well as the order in which they are usually acquired. The farther a student falls behind, the less that student will be able to leverage word identification instruction for learning to read.

However, there are too many words in students’ vocabularies to be able to provide explicit instruction for all of them. An average third grade student knows as many as 25,000 words. To reach college levels, students must acquire at least 100 words every school day after third grade. Therefore, some vocabulary instruction should be how to learn vocabulary by using word parts—suffixes and prefixes—and adding them to root words, increasing the number of words a student could command.

Beyond third grade, vocabulary becomes increasingly print-based and technical. Print becomes the dominant means by which vocabulary increases. Selection of vocabulary for instruction must be related to the content domain. As students progress through the grades, criteria for selecting words for instruction should change and go beyond the Tier 2 words that are often suggested as appropriate targets of instruction.

Vocabulary research does not dictate a single set of instructional technique for vocabulary instruction for all students. Rather, vocabulary instruction should change with students’ underlying reading proficiency.

Michael L. Kamil, who served as a member of the National Reading Panel, is a consulting professor of education at Stanford University.