Major analyses of the achievement tests used in the Beginning Teacher Evaluation Study were conducted to determine test reactivity to instruction. Reading and mathematics tests were administered to second and fifth grade children. Classroom teachers' records were examined to determine the amount of opportunity students had to learn the content presented; a matrix of student ability by opportunity to learn is included for each subtest. An analysis of the reactivity of the test items to instruction is also included. Test revisions, as dictated by reactivity analyses and other pilot test data, are described. Reactivity analysis is compared to standard psychometrics as a method of producing tests which are sensitive measures of classroom learning. (GDC)