The purposes of this study were to examine the utilization of audio modification in vocabulary assessment in school subject areas, specifically in elementary science, and to present a web-based key vocabulary assessment tool for the elementary school level. Audio-recorded readings were used to replace independent student readings as the task demand for progress monitoring science vocabulary for 162 fifth grade students in 14 schools. Scores on vocabulary tests obtained by students who used the audio texts for readings were compared with scores obtained by the same students who did not use the audio texts. A statistically significant difference between the two scores in favor of the students who used the audio texts was found. Benefits for at-risk students of school failure, and the trend between the amount of audio use and test scores were also investigated. Results suggest that, if appropriately conducted, the use of this type of modification together with written text may enable students feel confident about their science vocabulary knowledge. (Contains 1 table and 2 figures.)