Oklahoma City is home to the state's largest school district, Oklahoma City Public Schools. The district's Classen School of Advanced Studies and Harding Charter Preparatory High School rank high among public schools nationally according to a formula that looks at the number of Advanced Placement, International Baccalaureate and/or Cambridge tests taken by the school's students divided by the number of graduating seniors. In addition, OKCPS's Belle Isle Enterprise Middle School was named the top middle school in the state according to the Academic Performance Index, and recently received the Blue Ribbon School Award, in 2004 and again in 2011. KIPP Reach College Preparatory School in Oklahoma City received the 2012 National Blue Ribbon along with its school leader, Tracy McDaniel Sr., being awarded the Terrel H. Bell Award for Outstanding Leadership.

What is Oklahoma's largest school district?