Definition: A controversial teacher evaluation method becoming increasingly popular in school districts across the United States. This method measures a teacher's contribution in a given year by comparing the test scores of their students the previous year and taking into account the student's expected growth. The value added teacher evaluation also uses a comparison of scores of other students in the same grade. This model isolates the contribution that each teacher makes in a given year. A teacher's performance evaluation is therefore linked directly to how well their students perform on standardized testing.