Whether we’re measuring teacher skills or school performance, value-added evaluation continues to shape our definition of successful education. According to researchers at the Value-Added Research Center (VARC) at UW–Madison, a value-added model is simply a statistical formula that estimates the contribution of schools, classrooms, teachers, and other educational factors to student achievement. What makes value-added unique is that it also measures, and controls for, non-school sources of student achievement growth, including, for example, family education, social capital, and household income. Value-added models take into account that different schools serve very different populations of students. Controlling for non-school influences allows educators and researchers, like those at VARC, to make apples-to-apples school comparisons rather than apples-to-oranges comparisons. Value-added measurement provides one way to help determine the effectiveness of teachers and schools at the K–12 level and in postsecondary institutions.