Juniors and seniors at Oak Ridge High School lacked 75 minutes of instructional time each week.
The Tennessee Department of Education discovered the difference through a computer program that tracks instructional time for all school districts in the state.
Superintendent Tom Bailey said a 42 year-long lunch tradition at ORHS caused the time deficit.
Juniors and seniors, who are in good academic standing, were allowed to travel off campus for one hour lunch breaks.
To fill the 75 minute weekly void, school officials made two changes at ORHS.
The 60 minute lunch for juniors and seniors has been reduced to 50 minutes daily; freeing up 10 minutes each day for additional class time. That move adds 50 minutes weekly to the shortfall.
The other 25 minutes was created by longer class time. One minute was added to all five class periods; adding an extra 5 minutes of instructional time daily.
Dr. Bailey said the new changes at ORHS meet state standards for instructional time and the transition to the new schedule went smoothly.