In 1965 the authors conducted an experiment in a public elementary school, telling teachers that certain children could be expected to be “growth spurters,” based on the students' results on the Harvard Test of Inflected Acquisition. In point of fact, the test was nonexistent and those children designated as “spurters” were chosen at random. What Rosenthal and Jacobson hoped to determine by this experiment was the degree (if any) to which changes in teacher expectation produce changes in student achievement.