Development of Instructional Materials for teaching the Functions and the Mechanism of Transformers under at Alternating Current

Abstract

Instructional materials were developed for the functions and the mechanism of transformers that transmit electricity under an alternating current. Instructional materials comprising three units were developed as follows: (1) An experiment to compare the situation where a transformer was not used with the case where it was used. (2) An experiment to observe that the transformer works only at the time of the alternating current. (3) An experiment to observe electromagnetic induction occurring in the inside of the transformer. These instructional materials were piloted on the ninth grade students. The effectiveness of these instructional materials were determined by tests given to the students before and after the class. A follow-up test was given three months later to determine whether students still understood what they had studied. The follow-up test confirmed the effectiveness of the instructional materials. At the same time, it revealed that 21.9 % of the students didn't understand.