Numerous studies have shown a moderate correlation between vocabulary knowledge and reading comprehension in school children, and vocabulary knowledge varies substantially from student to student (c.f. Ouellette, 2006 ). Comprehending text on an unfamiliar topic is very difficult when one needs to learn a lot of new words specific to that topic. The problem is magnified, of course, for students with poor general vocabulary. For example, Hirsch (2003) states that in order to learn new words from a text, students need to be able to identify at least 90% of words in the text. Thus, when there are few unknown words and the text is coherent, comprehension proceeds more smoothly, and the reader can more easily learn the meaning of the new words he or she encounters. This happens because good comprehenders can usually derive the meaning from the context of a sentence or paragraph. However, a problem emerges when the number of unknown words becomes so great that students no longer have sufficient context to make an informed guess about the meaning.
So how do students acquire new words? Time constraints often limit teachers’ focus on vocabulary instruction in class. Instructional activities typically consist of selecting a set of low frequency words or new topic related terms from a text, learning and testing definitions for the selected words, discussing meanings, and encountering the words in the instructional text. How well do these activities match up with what we know about vocabulary learning in cognitive psychology? Does this pedagogy provide an effective way to teach vocabulary and enhance students’ comprehension of the texts that they are reading, allowing students to consolidate their new vocabulary into long-term memory?
Research suggests that repeated exposure to a new word in a context is the most effective way for words to be consolidated into memory (e.g., Butler et al., 2010; Lawrence, White, & Snow, 2010; McKeown, Beck, Omanson, & Pople, 1985 ). McKeown et al. (1985), for instance, found that vocabulary knowledge and reading comprehension scores were better when students had 12 exposures to a word compared to only 4 exposures. Similarly, Gardner (2004) found in a sample of 10-11 year-olds that the minimum sufficient number of times a new word needed to be encountered in text was 10. Furthermore, from around 12 -18 years of age, children typically learn 10-15 words per day on average primarily from reading text (c.f. Landauer and Dumais, 1997 ). In other words, students need to be interacting with lots of texts, so that they can have opportunities for repeated exposure to new words in order to store these words in long-term memory.
In our reading intervention, BRAVO, vocabulary is always taught in context, either with the teacher providing just-in-time vocabulary definitions as students are reading the text or when students are using the text to learn about new content. Thus, comprehension and vocabulary acquisition go hand in hand. Moreover, when students read multiple texts on a single topic, they are able to build knowledge from one text to the next that they can then use to provide a broader context for learning new vocabulary and improving comprehension in general. Vocabulary instruction is less effective when taught in the absence of context because it does not generalize beyond the activity itself (c.f. Goldman, 2012; Hollenbeck & Saternus, 2013 ). Therefore, in BRAVO, students learn new vocabulary in the context of multiple texts dealing with the same general topic or concept, so that their vocabulary and reading comprehension are jointly enhanced.