Complex sentence: Except for Lonsdale Elementary School, which only serves up to 4th grade, all of the cities in the district have full schooling up to 8th grade after which, students are served by Tri-City United High school.
Split into simpler sentences: Except for Lonsdale Elementary School, which only serves up to 4th grade, all of the cities in the district have full schooling up to 8th grade. After 8th grade, students are served by Tri-City United High school.