Complex sentence: After he turned ten, he was put in a class to prepare him for the state teachers examination, with older students and a few years later he was enrolled in a previously all-female seminary that doubled as a private boarding and day school.
Split into simpler sentences: After he turned ten, he was put in a class with older students to prepare him for the state teachers examination. A few years later he was enrolled in a previously all-female seminary that doubled as a private boarding and day school.