Complex sentence: He taught at the high school for the next five years while earning a M.A. in Liberal Studies from Reed College in 1978, followed by a M.S. in Mathematics from Portland State in 1981.
Split into simpler sentences: He taught at the high school for the next five years. While doing so he earned a M.A. in Liberal Studies from Reed College in 1978, followed by a M.S. in Mathematics from Portland State in 1981.