Teaching computing in K-12 is typically accomplished by teaching algorithms and programming through hands-on activities in which students create software artefacts with block-based platforms such as App Inventor. This approach, following the Use-Modify-Create cycle, can guide students from developing predefined mobile applications, to modify these apps and guide them to idealise their own apps by adopting design thinking practices as part of an agile software engineering process. In this context, this chapter presents a course that was developed following an instructional design process and applied and evaluated in Brazilian public middle and high schools with students aged 9–20 years. Our results indicate that such a learning strategy can have a positive impact on student learning, motivation and the learning experience. Furthermore, teaching computing through a design thinking-based development of mobile applications keeps students engaged by the opportunity to create useful and usable solutions with an impact on their communities. It also seems to help them develop important twenty-first-century skills, such as creativity, problem resolution and critical thinking while learning computing.