Vocabulary Assessment and Instruction
Oral vocabulary, or knowledge of word meanings, plays a key role in reading comprehension. If children are unfamiliar with the meanings of words in a text, their comprehension will suffer, even if they can decode the words. For example, if a child can sound out the printed word scarlet in a sentence but does not know that scarlet means red, some comprehension will be lost; if this experience is repeated with a number of important words in the text, then comprehension will be seriously impaired.
Although vocabulary is critical to reading at all stages of development, the vocabulary demands of the texts used in school escalate greatly beginning at about a fourth-grade level. Therefore, children with vocabulary weaknesses are especially vulnerable to difficulties with reading comprehension from the middle elementary grades onward. Furthermore, vocabulary weaknesses may affect school achievement in many areas beyond reading, including written expression, mathematics, and performance in content subjects such as social studies and science.
Vocabulary and Learning Disabilities
Vocabulary knowledge varies greatly in individuals with learning disabilities (LDs). For some youngsters with LDs, vocabulary can be an area of strength. For instance, children with dyslexia or specific reading disabilities may have above-average oral vocabularies despite having phonological weaknesses that adversely affect the development of decoding skills. These youngsters may have excellent listening comprehension, as well as the ability to dictate stories with strong verbal content. For other children with LDs, such as those with more generalized language difficulties (but typically average or better nonverbal abilities and social functioning), vocabulary weaknesses can be part of a broader language impairment. Of course, vocabulary knowledge for individuals with LDs also is affected by experience and opportunities to learn new words, just as it is for all children. For example, whether or not they have learning disabilities, children who are often read to at home and whose teachers address vocabulary in instruction will have more exposure to words and better prospects for vocabulary development.
Assessment of Vocabulary
Assessment of vocabulary is critical for identifying children at risk for reading problems and for designing appropriate instruction. The use of oral measures is essential. Tests that require reading or writing make it impossible to differentiate other problems children may have, such as difficulties in word decoding or spelling, from lack of vocabulary knowledge. Children with suspected learning disabilities should be individually assessed on measures that include both receptive and expressive oral vocabulary. Receptive vocabulary involves understanding of spoken words, for instance, asking a child to point to a picture that represents a word spoken by the examiner. Expressive vocabulary involves using or naming a word, as when the examiner shows a picture to a child and asks the child to name it. Although the relationship of receptive vocabulary to reading comprehension seems obvious, expressive vocabulary appears to be an even stronger predictor of beginning reading achievement than is receptive vocabulary. Therefore, both areas should be included in a comprehensive assessment.
Reprinted with the permission of LD OnLine. © 2008 WETA. All Rights Reserved.