The term GRADE SCH. CLASS is composed of three parts: ENG (3 letters), SCI (3 letters), and CLASS. ENG stands for English, which is a language subject typically taught in schools. SCI stands for Science, which is a subject that covers topics such as biology, chemistry, and physics. CLASS is short for Classroom, which is the physical space where students learn. Together, these three components form the term Grade School CLASS, which refers to a CLASS of students in elementary or middle school.