The importance of vocabulary knowledge is no more apparent than in its contribution to reading comprehension. In fact, an enduring finding of reading researchers is how much vocabulary knowledge influences reading comprehension (e.g., Anderson & Freebody, 1981; Baumann et al., 2003; Becker, 1977; Davis, 1942; NRP, 2000; Whipple, 1925). Research tells us that real comprehension cannot happen without adequate vocabulary. Readers need to know between 95% and 98% of the words in a text to successfully comprehend it (Hsueh-Chao & Nation, 2000; Laufer, 1989; Schmitt et al., 2011). Further, broad vocabularies have been found to help with word decoding by giving students a way to confirm that what they sound out is actually a word (e.g., McBride-Chang et al., 2005; Mezynski, 1983).
So, while we know vocabulary’s importance in reading, what is it? So often in classrooms, vocabulary is simplified to be 8-10 isolated words that students are to learn during the week. Basal reading programs identify the words to focus on, and provide definitions, weekly activities, and an assessment that likely asks students to match the words to their definitions. This type of vocabulary routine was something I experienced as a teacher and continue to see in classrooms today. But is that vocabulary routine enough?
Based on what research tells us, the simple answer is: No! First, it is impossible to learn enough vocabulary to thrive by direct instruction alone. Second, words live in sentences, which live in paragraphs and larger texts. Teaching words in isolation neglects the context within which the word lives. To really build vocabulary knowledge, we need to move past the definitional level and learn to handle the subtleties and complexities of syntax, context, and funds of knowledge.
A simplified explanation of vocabulary is the body of words known to an individual person. However, vocabulary also refers to all of the words included in a language. According to Payack (2023), English has over 1 million distinct words. The sheer number of words in English highlights the need to acquire more than 8-10 words per week as mentioned above; at that rate, the student will only learn 3,250 words in 13 years of school (10 words x 13 years x 25 instructional weeks). It is easy to see that direct instruction alone will not be sufficient enough to acquire the quantity and quality of word knowledge required to be literate in today’s society.
Educational researchers have theorized various constructs to demonstrate the difference between words. For instance, Beck, McKeown, and Kucan (2002, 2008) proposed a 3-tiered system of words. Tier 1 words are those used in everyday conversation. The language used is informal and used when communicating with friends or family, either in writing or in conversation. Tier 2 words are general academic words that are used across content areas (e.g., science, social studies, math). These words help to construct academic texts. For instance, the word analyze can be used in language arts to analyze a novel, in history to analyze a historical account, and in science to analyze the results of an experiment. Understanding the meaning of tier 2 words is critical for comprehending academic texts.
Tier 3 words are found in specific domains and less frequently in non-discipline specific usage (Beck et al., 2002, 2008; Coleman & Pimentel, 2011). Tier 3 words have also been called technical terms (Harmon, Wood, & Medina, 2009) that value precision in meaning (Fang, Schleppegrell, & Cox., 2006; Snow, 2010; Snow & Uccelli, 2009). For instance, scientific words, such as fumarole and lahar are unique to volcanology, have precise meanings, and are not used across disciplines.
Distinguishing between the different types of words is important for instruction, as is knowing how vocabulary knowledge develops. Vocabulary knowledge development includes more than memorizing a definition (Johnson & Pearson, 1984; Nagy & Scott, 2000), it is multifaceted with word knowledge acquisition occurring incrementally.
Researchers have conceptualized vocabulary development in multiple ways with the understanding that knowing the meaning of a word is not all or nothing (Beck & McKeown, 1991; Nagy & Scott, 2000). Research commonly recognizes the progressive development of word knowledge that can vary from not knowing a word, to knowing parts of the word, to being able to use it in a sentence, to being able to know how it relates within a complex network of disciplinary knowledge. Dale (1965) proposed dimensions of knowing a word with 4 incremental stages:
Between stages 3 and 4, vocabulary knowledge moves from receptive to productive. Receptive vocabulary refers to the capability to comprehend the meaning of a word when a student hears or sees the word as compared to being able to use the word in writing or speech, which is productive vocabulary (Zhou, 2018). Words develop through phases as a student gains more knowledge about the word, then through repeated exposure and learning, they begin to use the word until they reach stage 4. At this stage, a student knows synonyms of the word and the meaning of polysemous words, words with more than one meaning. Knowing the multiple meanings of a word includes knowing the precise and general meanings of a word. For instance, knowing a word well, such as prime, includes knowing the precise meaning, as in math, of a number greater than one that is not the product of two smaller numbers as compared to its general meanings of high quality or of first importance. This example leads to another important point: vocabulary does not develop in isolation.
The importance of assessing vocabulary is well-established in schools as evidenced by students often completing weekly assessments to measure their ability to remember the meaning of the words of the week. However, using vocabulary measures to identify students who may be struggling to read proficiently is not as widely employed. Given vocabulary’s influence on comprehension, evaluating vocabulary knowledge with a simple and quick yet reliable measure helps to determine which students require additional support.
When selecting a measure, it should include mostly tier 2 words with some tier 3 words and be designed in a way that measures word knowledge in isolation and in context. When students complete a vocabulary assessment that does not present words in context, they have to know the meaning of the word without relying on the context to guess the word. Having students select a synonym (e.g., smart—intelligent) of a given word or match a topical associate (e.g., voice—talking) are two ways to measure word knowledge without providing a context.
Measuring vocabulary knowledge within context is also important as it captures what students can do with the words they know (American Educational Research Association, 2015). Providing context allows students to show whether or not they know the general meaning of a word or the meaning that belongs within the sentence. While many vocabulary assessments exist, ETS ReadBasix quickly measures vocabulary knowledge in both isolation and in context. The vocabulary subtest employs synonyms and meaning associates to measure students’ vocabulary knowledge with no context provided, while the reading comprehension subtests measure vocabulary knowledge in context. You can find out more about how ReadBasix assesses vocabulary here.
Ensuring meaningful vocabulary instruction in the classroom rests on the educator’s ability to measure what students know. Educators of all grades need to have the tools that help identify gaps and monitor progress so that students’ vocabulary development can be supported to aid in successful reading comprehension.
We look forward to more conversations about the Science of Reading and how to best support reading comprehension. If you have a question about the Science of Reading or would like us to consider a specific topic, let us know here.