Partial word knowledge and vocabulary growth during reading comprehension

The experiment investigated the development of vocabulary knowledge in elementary school children as a function of story reading for partially known and unknown words. Fourth graders participated in a vocabulary checklist in which they provided definitions or sentences for words they knew (known words) and checked off words they did not know the meaning of but were familiar with (partially known words). Children then read stories containing some of these words. The remaining words served as a control. Vocabulary growth was small but even for both partially known and unknown words. However, the characteristics of the words being learned themselves (particularly, part of speech and concreteness) were more important in determining this growth than aspects of the texts.