Starting in 2006, a "flex" day was added to the cycle. During each cycle, one of the cycle days is split into two calendar days. On the first of these "flex" or "block" days (known as "Odd Block"), students attend periods 1, 3, 5, and 7 for almost twice as long as they normally would. The following day, on "Even Block," students attend periods 2, 4, 6, and 8. During the 8th period, which does not exist during a non-block day, students may receive remedial education or attend club meetings. The 8th period is divided into two normal-length periods, which are known as 8A and 8B. This gives the students greater choice of how to spend their time. As of the 2007-2008 school year, students are required to go to their homerooms before and after 8th period (but not between 8A and 8B) for an attendance check.
Great Valley High School is a member of the Pennsylvania Interscholastic Athletic Association. Students are subject to guidelines and principles determined by this organization. More locally, Great Valley is a member of the Chesmont League and PIAA's District One region. It used to belong to the now defunct Southern Chester County League.The high school offers athletics in all high school grades. In addition, it has an intramural program. The athletic director as of 2006 is Mr. Russel Wren. The school has been to and won various state championships. The most recent girls state championship win was by the lacrosse team in 2005. The most recent appearance was in 2006 when the boys soccer team lost in the championship game, but they did win states in 1993.