Complex sentence: Innovation Academy Charter School was created in 1996 by a group of parents in Chelmsford, Massachusetts, its first class of middle school, grades 5-8, was made up of 150 students.
Split into simpler sentences: Innovation Academy Charter School was created in 1996 by a group of parents in Chelmsford, Massachusetts. Its first class of middle school students, grades 5-8, was made up of 150 students.