The ubiquity and educational potential of mobile applications are well acknowledged. This paper proposes six theory-based, pedagogical strategies to guide interaction design of mobile apps for young children. Also, to augment the capabilities of mobile devices, we used a humanoid robot integrated with a smartphone and developed an English-learning app that applied the design strategies to this environment. Our observations of children's one-on-one use support the promise of the strategies and the combined use of robots and mobile devices to be a viable option to help optimize mobile learning.