• GVMS Athletics Great Valley Middle School is a member of the PIAA (Pennsylvania Interscholastic Athletic Association) and is subject to the guidelines and principles set forth by this governing organization. Locally we are a member of the CHES-MONT League and PIAA's District One. Great Valley offers 15 sports for students in grades 7-8.  Use the links on the left to obtain further information on Great Valley Middle School Athletics.