There is a significant concern about students’ achievement in reading comprehension. The study examined the reliability, validity, and slope of curriculum based measures in a content specific area – science. Participants included students in 6^th grade science classes. The curriculum based measures (CBM) being used consisted of vocabulary-matching probes that were administered weekly, each probe having 20 vocabulary words and 22 definitions included. Terms and definitions were based on current material being learned by the students (Science Fusion) and Next Generation Science Standards terms. The criterion measures were the students’ performance such as student grades and standardized test scores on the science portion of the Illinois Science Assessment (ISA), which were taken at the end of the previous school year. It was hypothesized that the CBM measures would demonstrate adequate reliability, validity, and detect student progress and performance. However, little research has been conducted over the development of vocabulary matching measures on science curriculum performance and progress.