Complex sentence: Skyline High School was created in the fall of 1966, but due to incomplete construction, neither of the first two graduating classes (1967 or 1968) actually attended classes at the high school.
Split into simpler sentences: Skyline High School was created in the fall of 1966. However, due to incomplete construction, neither of the first two graduating classes (1967 or 1968) actually attended classes at the high school.