This study investigated 8th-grade science students (13-14 years old) in advanced and traditional ability classrooms perceptions of their vocabulary knowledge, learning, and content achievement. This research acknowledges the critical role that developing vocabulary knowledge from reading plays in gaining a deeper content understanding as well as promoting overall science literacy. Data sources included pre- and post-test of students' perceptions of vocabulary knowledge, students' perceptions of vocabulary and reading strategies surveys, and a content achievement test. Students' perceptions of vocabulary knowledge were compared before and after instruction to see whether students believed they gained knowledge and the ability to explain categories of technical science terms. Students' in both advanced and traditional classroom perceptions of vocabulary knowledge increased as a result of instruction. The participants had favorable views of the vocabulary and reading strategies implemented and believed that the literacy approaches were important for their developing scientific knowledge. Furthermore, students' content achievement was compared for the advanced and traditional groups. Although advanced class classes outperformed traditional courses on the content test, only one of the seven items was statistically significant. Both groups were compared to a national data set that served as a control and had statistically significant higher achievement than the national data set. Most of the inferential measures indicate that there is no statistically significant difference between the two groups. The combination of metacognitive awareness, close reading, and integrative vocabulary helped all students build complex schema surrounding science vocabulary, as evidenced by student's perceptions of knowledge and their content achievement. This study is one of the first to highlight the pivotal role students' perception of vocabulary knowledge and vocabulary and reading strategies plays in science content learning regardless of ability level.