Complex sentence: The Haliwa-Saponi's latest and most exceptional accomplishment is the opening of the Haliwa-Saponi Tribal School, which is 98% Indian, and boasts a curriculum based on standard course of study, small classrooms, technology, and American Indian Studies.
Split into simpler sentences: The Haliwa-Saponi's latest accomplishment is the opening of the Haliwa-Saponi Tribal School, 98% of whose students identify as Indian. The school has a curriculum based on standard course of study, small classrooms, technology, and American Indian Studies.