Thunderbird High School was scheduled to open its doors in the fall of 1972, but unfinished construction forced Moon Valley's campus into double sessions to accommodate Thunderbird students. There were approximately 1,110 T-Bird students attending from 1 – 5:45 p.m. Moon Valley’s students attended in the morning. Principal Ed Cosper managed forty-nine teachers who taught the 1,100 freshman and sophomore students that first year. The first graduating class was at the end of the 1974-75 school year.