Demonstration kits for locating an image formed by a concave mirror

Abstract

To improve student understanding about an image formed by a concave mirror, 2 demonstration kits were developed. One kit is used to view and locate images formed and find the image distances and sizes. The other uses a laser beam to show the incident and reflected light rays and relate to the ray diagram normally used to find the image location. The demonstration kits were applied to year-11 Thai high-school students for both online (N = 32) and on-site (N = 22) classes. The 4 diagnostic questions were used to investigate student understanding, covering the image visualization, the mirror equation, and the ray diagrams of a concave mirror. The mean scores of the pre- and post-test are 1.3 and 5.3 out of 13, respectively, and the averaged normalized gain is 0.34. Interestingly, the normalized gains of the two classes are not significantly different indicating that the demonstration kits can be applied to either an online or on-site class. The best improvement was found in the image visualization question. In addition, the demonstration kits make the physics content enjoyable. The students found it exciting and fun while much is being learned.