Illini West High School in Carthage will switch to an eight-block class schedule for the 2013-2014 school year.
Classes will meet five times every two weeks. Students will take four classes each day.
Teachers might have the most to learn during the transition.
Superintendent Kim Schilson said they will have to adapt to teaching 90-minute periods.
The district will offer teachers a great deal of professional development to ease the transition.