Vocabulary Development and Word Characteristics in Deaf and Hearing Pupils

Persistently, most deaf children get stuck at a grade 3 reading comprehension level. Vocabulary knowledge predicts reading comprehension best. We longitudinally measure two forms of vocabulary knowledge of deaf children of different instructional ages, matching them with hearing children both on instructional age and on reading age. We relate the results to particular word characteristics and, thereupon, develop and test a measure for word difficulty. Also, we relate results to an existing model for the adult vocabulary, and to the expected vocabulary development for Dutch children, derived from CITO-language-testing materials. The study yields fundamental new theoretical as well as practical knowledge.