Breadth and depth: must-haves in any vocabulary


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Breadth and depth: must-haves in any vocabulary

Wednesday, 4 Sep 2019

Ahead of International Literacy Day on Sunday 8 September, we take a closer look at vocabulary skills and their role in literacy learning progress. ACER Principal Research Fellow and PAT test developer Prue Anderson reviews the research that informed the test design.

As an educator, you’ll know from practical experience that strong vocabulary skills aid reading comprehension. That experience is backed up by the research, which concludes that a rich vocabulary is essential to developing listening and reading comprehension from the earliest years1,2,3. Children with preschool teachers who actively develop their language skills – by modelling the use of more sophisticated vocabulary, engaging children actively in talk about books and using more complex syntax themselves – demonstrate higher levels of literacy achievement in later years4. Vocabulary appears to be more important than grammar or short-term memory in enabling four- to five-year-old children to make inferences5. As early as second grade, children with larger vocabularies read words more accurately6, and an even stronger relationship between a rich vocabulary and good comprehension emerges in later years when students read more complex texts7,8,9.

A 1994 study10 found that children with poor language and vocabulary skills in the early years of school were the lowest achievers in reading and related literacy skills, and in language and vocabulary skills, seven years later. Children who enter school with lower vocabulary scores tend to come from home backgrounds where they hear fewer different words per interaction, hear more commands rather than prompts and questions, and have less interaction with adults11. Language-rich early years’ environments are critical.

How vocabulary skills aid learning

Having a broader vocabulary helps students understand enough of the texts they hear or read to infer meaning in confusing parts, allowing them to continue to improve their vocabulary by learning new words in context and to further develop their comprehension skills. Students with low levels of literacy struggle to learn new words in context because there are too many words they do not know, so there is little support in inferring meaning. This contributes to the Matthew effect12, a downward spiral in which early lags in literacy become magnified as reading skills develop; when students read, those with rich vocabularies rapidly expand them through successfully inferring the meaning of new words, while students with poor vocabularies show little vocabulary growth.

Supporting a student’s growth in vocabulary supports their educational progress. Those with limited vocabularies will inevitably have limited comprehension skills. Students need to understand at least 95 per cent of what they read in order to continue to improve their reading comprehension skills; below 90 per cent, students no longer improve comprehension through independent reading13.

How does vocabulary develop?

Teachers who understand how vocabulary develops are able to plan vocabulary instruction in a sensible, progressive and effective way. Here are two influential approaches to describing vocabulary development.

The first separates vocabulary into three tiers14. Words in tier one are familiar, everyday words that are not conceptually difficult; they are encountered frequently and often, and so are necessary knowledge for language use. Tier two words are more complex but are used regularly and across a variety of contexts, and so will need to be learned in order to continue to develop language skills. Tier three words are infrequently used, specific to particular contexts or topics, and are used more in written rather than spoken language.

The second approach15 divides vocabulary into familiar and unfamiliar words, then organises unfamiliar words into one of four categories determined by the relative importance of knowing the meaning of the word in understanding the text in which it appears. Ordering categories by importance lends itself to recommendations of pedagogical strategies for ensuring more important words are explicitly and carefully taught, but less important words receive less attention. However, importance is decided in the context of the age and ability of the students; categories are not fixed, allowing for instructional planning to be responsive to the needs of the students.

Both approaches take into account the frequency and complexity of words and assume that the simplest and most familiar words ought to be taught and mastered first, to form a foundation from which to build upwards and outwards. This is a traditional and common sense approach, and one that appears to be effective.

Designing a test of vocabulary skills

Test design is a complex and evolving field, of which this Victorian Government guide gives a good overview, but let’s look briefly at the basic design of PAT Vocabulary Skills. The assessment uses the foundation-building approach described above, so that questions in early test forms tend to focus on understanding familiar, frequently-used words, while later test form questions include a greater proportion of words that are used less frequently. Progression is indicated in test question descriptions, where words are referred to as ‘familiar’, ‘common’, ‘uncommon’, or ‘rare’.

Questions were developed with reference to word frequency in several large bodies of writing16 in order to determine how frequently a word was likely to be encountered when reading. Probable contexts were taken into account, and question descriptions were revised based on feedback from trials on perceived difficulty. For example, ‘eyelid’ is not in the top 20,000 most frequently used words in the British National Corpus (it is ranked 23,378) so, had we only considered word frequency, it would have been described as ‘uncommon’ or ‘rare’. However, words for body parts are taught to quite young students and, considered in that context, ‘eyelid’ is a better candidate for being a ‘common’ word. This example was not used in questions in PAT Vocabulary Skills, but trial results indicating the low difficulty of other questions targeting vocabulary relating to body parts confirms that students are familiar with such words, making them suitable for inclusion in test forms for younger students.

Vocabulary breadth and depth

Categorising words by difficulty is just part of the test design story. Breadth of vocabulary – that is, knowing the meaning of a large number of words – is an important factor but depth is significant too17. Depth is indicated by factors like the richness of a student’s word associations, their understanding of how and where a word is commonly used, and how context alters word meaning.  Can a student determine the meaning of a familiar word used in an unfamiliar way? Can she use context to infer meaning of a brand new word? Word knowledge is crucial but additional conceptual skills are needed to apply that knowledge.

PAT Vocabulary Skills was designed to measure abilities like knowing, applying and categorising words, in addition to understanding and using morphology. It uses a single scale to report on student performance across the range of vocabulary skills, with bands describing the types of skills and knowledge typically associated with that level of achievement. These descriptions help teachers understand where students are in their learning and target teaching where it is needed most, and to monitor performance over time, so that all students can demonstrate learning progress.

With Australia’s Programme for International Student Assessment (PISA) results in reading in decline, it’s time to look at the role assessment can play in making sure our students are learning the skills they need to progress in their learning. ■

Find out more about the ACER Progressive Achievement (PAT) approach.


1: Graves, M. F. (2006). The vocabulary book: Learning & instruction: Teachers College Press.

2: Hairrell, A., Rupley, W., & Simmons, D. (2011). The state of vocabulary research. Literacy Research and Instruction, 50(4), 253-271.

3: National Reading Panel. (2000). Teaching children to read: an evidence-based assessment for the scientific research literature on reading and its implications for reading instruction: Reports of the subgroups. Bethesda, MD: NICHD

4: Dickinson, D. K., & Porche, M. V. (2011). Relation between language experiences in preschool classrooms and children’s kindergarten and fourth‐grade language and reading abilities. Child Development, 82(3), 870-886

5: Silva, M., & Cain, K. (2015). The relations between lower and higher level comprehension skills and their role in prediction of early reading comprehension. Journal of Educational Psychology, 107(2), 321-331.

6: Snow, C. E., Tabors, P. O., Nicholson, P. A., & Kurland, B. F. (1995). SHELL: Oral language and early literacy skills in kindergarten and first-grade children. Journal of Research in Childhood Education, 10(1), 37-48.

7: National Early Literacy Panel. (2008). Developing Early Literacy: Report of the National Early Literacy Panel, a scientific synthesis of early literacy development and implications for intervention. Washington DC: National Institute for Literacy.

8: Storch, S. A. & Whitehurst, G. J. (2002). Oral Language and code-related pre-cursors to reading: Evidence from a longitudinal model. Developmental Psychology, 38, 934-947.

9: Senechal, M., & LeFevre, J. (2002). Parental involvement in the development of children’s reading skill: A five-year longitudinal study. Child Development, 73, 445-460.

10: Walker, D., Greenwood, C., Hart, B., & Carta, J. (1994). Prediction of school outcomes based on early language production and socioeconomic factors. Child Development, 65(2), 606-621.

11: Hart, B., & Risley, T. R. (1995). Meaningful differences in the everyday experience of young American children: Paul H Brookes Publishing.

12: Stanovich, K. E. (1986). Matthew effects in reading: Some consequences of individual differences in the acquisition of literacy. Reading research quarterly, 360-407.

13: Allington, R. L. (2012).What really matters for struggling readers: Designing research-based programs (3rd Ed). Boston: Allyn and Bacon.

14: Beck, I. L., McKeown, M. G., & Kucan, L. (2013). Bringing words to life: Robust vocabulary instruction (2nd ed.): Guilford Press.

15: Graves, M.F, Baumann, J.F., Blachowicz, C., Manyak, P., Bates, A., Cieply, C., Davis, J., & Von Gunten, H. (2014). Words, Words Everywhere, But Which Ones Do We Teach? The Reading Teacher 67(5), 333-346. DOI:10.1002/trtr.1228.

16: British National Corpus; Corpus of Contemporary American English; Oxford Children’s Corpus

17: Haastrup, K. & Hendrikson, B. (2000). Vocabulary Acquisition: Acquiring depth of knowledge through network building. International Journal of Applied Linguistics 10(2), 221-240