In the late 1930s, an ambitious graduate student named Herbert F. Spitzer asked thousands of Iowa sixth graders to read a short article about bamboo – an article he later described as “highly factual, authentic, of the proper difficulty, and similar in type to the material that children read in their regular school work.”
He divided the students into 10 groups and gave them long multiple-choice quizzes (“What usually happens to a bamboo plant after the flowering period?”) at varying intervals. One group, for example, was quizzed immediately after reading the article, then again the next day, and then a final time three weeks later. Another group was quizzed only once, three weeks after reading the article. The students did not know when they would be quizzed, and they did not keep the article, so they had no chance to study on their own.
The results were striking: On tests three or nine weeks later, students performed far better if they had previously been quizzed within 24 hours after first reading the article. When Mr. Spitzer wrote up his work in the Journal of Educational Psychology in 1939, he made a recommendation that might have made millions of students and their teachers groan: “Immediate recall in the form of a test is an effective method of aiding the retention of learning and should, therefore, be employed more frequently in the elementary school.”