The effectiveness of training aids in the teaching of elementary electronics trouble shooting was tested. Students entering the Basic Electronics course at the U.S. Naval Training Center, Great Lakes, Illinois, were assigned to one of three groups being taught by either the standard Navy training method using actual operational equipment, training with actual equipment plus the Trainer-Tester, or training with actual equipment plus the Punchboard Tutor. The Trainer-Tester device presented the student with a list of the symptoms exhibited by a malfunctioning piece of equipment and required him to conduct a number of hypothetical tests and measures until he could determine the cause of the malfunction. The Punchboard Tutor device provided students with immediate correction of multiple choice questions. The performance of the three groups on examinations, laboratory grades, and overall performance was compared. Follow-up data on those trainees who went from the Basic Electronics course into Advanced Radar and Communication Schools was obtained. Students who used the training devices received higher overall grades than students who used equipment only. In Advanced Radar Training the Trainer-Tester users received better grades in Radar Laboratory. (KB)