The emergence of the Internet of Things (IoT) has had a transformative effect on our society and has inspired educators to develop innovative approaches to educate the next generation of Computer Science (CS) professionals. This paper presents the design and development of an introductory IoT course suitable for grades 9-12 Computer Science classes. Information about the course content, intended outcomes, and evaluation techniques are presented. The course was introduced in 2 high schools in the US. The course includes a capstone project where the students identified a real-world problem and developed an IoT-based solution to address it. Formative and summative technical evaluation results are presented and suggest that the course provided an effective learning experience for students. The information presented here provides guiding principles for developing an IoT-based curriculum geared towards 9-12 education while also exposing the students to CS fundamental.