In a contest featuring hands-on projects, college students were required to design a simple crawling worm using planning, self-monitoring and self-evaluation processes to solve contradictive problems. To enhance the efficiency of problem solving, one needs to practice meta-cognition based on an application of related scientific concepts. The objective of this study, then, was to analyze the physics concepts employed by the students as they completed a hands-on project named "Crawling Worm," during which they had to overcome problems encountered by the requirements of their design as well as those brought on by competition. Based on the analysis of the participants' working portfolios and on reviews and interviews by engineering professors, the results of this study show that the crawling worm design competition encouraged the practice of problem solving, and it facilitated the learning of physics concepts such as friction, torque, four bar link, material properties, and so on.