Standardized testing has been used in public schools in the United States since the 1840s when written tests began replacing oral exams. Major developments include the first statewide standardized test in Iowa in 1929 and the adoption of the Common Core State Standards in 2010. While standardized tests are controversial, they can be useful for comparing student and school performance across large areas as well as identifying strengths and weaknesses to guide improvement efforts. Effective classroom assessments include both informal techniques like minute papers and one-sentence summaries as well as formal standardized tests. A balanced approach to assessment is important for student learning and evaluation.