Complex sentence: Glenn performed as two-way lineman at Bishop O'Dowd High School in Oakland, California, and later attended the University of California, Berkeley, where he was a four-year letterman and two-year starter.
Split into simpler sentences: Glenn performed as two-way lineman at Bishop O'Dowd High School in Oakland, California. He attended the University of California, Berkeley, where he was a four-year letterman and two-year starter.