Value-added methods are tools that analysts have devised to help people understand the gains that students are or are not making while in school. This can be done in many ways, and different analysts and states have developed various approaches. Beginning in August 2008, Ohio's academic accountability system includes a value-added component that measures student academic progress in addition to achievement. Value-added changes how Ohio evaluates its public schools. This short primer on value-added was designed to help business people, lawmakers, policymakers, and others understand this powerful, but complex tool. (Contains 4 figures.)