Complex sentence: The new building officially opened to students and staff in August 2000, just in time for the new school year, thus becoming the first new high school constructed in Prince George's County since Eleanor Roosevelt High School was completed, back in 1976.
Split into simpler sentences: The new building officially opened to students and staff in August 2000, just in time for the school year. It was the first new high school constructed in Prince George's County since Eleanor Roosevelt High School was completed in 1976.