Promote Student Understanding on Projectile Motion Using Inquiry-based Learning Approach : A Case Study for Cambodian 11th Graders

Abstract

This research aims to promote 11th graders' understanding of projectile motion through the Inquiry-Based Learning (IBL) approach in a Cambodian high school context. The participants involved were 204 11th graders from three high schools located in three different regions in Cambodia. The test of Conceptual Questions on Projectile Motion (CQPM) consisting of 7 open-ended questions was developed to survey and identify projectile motion misconceptions of 124 students on pre-test and 131 students on post-test at 11th grade in one high school in year 2016. The obtained preliminary results and the Cambodian curriculum served as a basis to design the IBL procedure, which addressed how to guide the students from their misconceptions to the correct scientific concept in projectile motion. The CQPM embedded with 10 related projectile motion concepts such as the direction of velocity and the direction and magnitude of acceleration of a projectile, direction and magnitude of force acting on the projectile, the time interval of the simultaneous vertical and horizontal motions, the splashdown speed and the acceleration of vertical and horizontal motion, the horizontal distance and final velocity of the projectile when the time interval changes, projectile trajectory, the acceleration of linear motion, and the acceleration of circular motion. Our main data, the students' responses to CQPM on pre and post-tests after the IBL instruction in year 2017, were quantitatively and qualitatively analyzed by average normalized gain (<g>) and model analysis. It was found that <g> of all questions in CQPM was in medium gain (<<g>> = 0.44± 0.03), which shows that the designed IBL is an interactive-engagement teaching method, more effectively improving students' understanding of projectile motion than traditional teaching methods. IBL improved the concepts of flight time of simultaneous projectile and free- fall motion events, and the trajectories of a projectile. However, there were low gains in some concepts such as the projectile's velocity direction, magnitude and direction of a projectile's acceleration, and magnitude and direction of force on a projectile. The average gain for each concept varied owing much to the demonstration set-up in the IBL procedure. Further, we found that IBL procedure supported students to transfer their mental model from an incorrect model region to a mixed model region regarding the concept of the projectile trajectory. It is suggested that variables in different contexts with identical concept are challenges when students had more than one popular misconception. The demonstration set-up has to be good enough to address most the students' misconceptions in each context. Our confronting difficulty in Cambodian high school context is still a lack of the facilities of teaching media such as computers and projector screen. These challenges need to be taken into consideration to achieve a satisfactory outcome in future research.