Ninth grade
Though the 2001 expansion was projected to accommodate the school's population for decades, the student population grew rapidly. It was decided that neighboring Chester Middle School would be shut down due to budget cuts and the overcrowding at Thomas Dale, thus the high school annexed Chester Middle. Ninth graders are currently housed at the former Chester Middle School, now known as the Thomas Dale Ninth Grade Campus, while 10th - 12th graders are at the main campus.