Since the late twentieth century, with the development of the Internet of Things (IoT), the IoT covers the application of comprehensive knowledge and technology in the fields of circuitry, physics, mechanics, and information, making it a suitable topic for hands-on science, technology, engineering, and mathematics (STEM) activities. The IoT covers a large amount of knowledge, practical skills, and programming skills in STEM fields, both teaching and learning the content can be difficult. Thus, this study used gamification with the 6E model and the software development method as the teaching strategies to explore their effects on high school students' computer programming self-efficacy, IoT knowledge, and hands-on performance in IoT learning activities. In this study, a quasi-experimental design was used for 12 weeks, and the 132 students who participated in the experiment were divided into Experimental Group 1 (EG1, 66 students using gamification with the 6E model), Experimental Group 2 (EG2, 31 students using the 6E model only), and the Control Group (CG, 35 students using the software development method). Through Analysis of Covariance, the results showed that the students in EG 1 achieved higher academic performance in terms of computer programming self-efficacy, IoT knowledge, and hands-on skills. The results of the lag sequence analysis of behavioral patterns showed that all the students required frequent two-way communication with the teachers and needed to communicate with their group members. The students in EG 1 exhibited positive interactions and took the initiative in asking for help from other students, which indicated that the students in this group achieved better learning outcomes. In addition, those interested in exploring STEM hands-on activities would benefit from our findings.