Complex sentence: North Shore Senior High School is a 10th 11th and 12th grade campus with the addition of 10th grade (in 08), which originally opened in 1962, but relocated to a new campus in the spring of 1999.
Split into simpler sentences: North Shore Senior High School is a 10th, 11th and 12th grade high school campus. It originally opened in 1962 but relocated to a new campus in the spring of 1999.