Christothea Herodotou is a Lecturer in Innovating Pedagogy at The Open University, UK. She is interested in the design and use of innovative technologies, in particular web-based technologies, digital games and mobile applications for learning and their relationship to human motivation and cognition. She is also particularly interested in how learning analytics can inform our understanding of the use of technologies and improve the learning experience. She has recently received funding from the British Educational Research Association (BERA) to examine the learning impact of mobile applications on young children under the BERA BJET Fellowship. Address for correspondence: Dr Christothea Herodotou, Institute of Educational Technology, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK. Email: christothea.herodotou@open.ac.uk Abstract A popular activity among young children is the use of mobile devices and apps. Yet, the impact of mobile devices on learning and development is rather underexplored. The limited studies identified explore effects on literacy development and communication and report on mixed findings. A considerable gap is observed as to how the use of mobile apps relates to young children's understanding in diverse domains including science learning, and to extend, whether and how mobile apps should be used and how in early years' settings. The aim of this paper is to shed light on this area by examining the learning effects of touch screen mobile game applications, in particular the game Angry Birds, on two groups of preschoolers 4 and 5 years old respectively. Evidence from a comparative study with 32 participants reveal significant differences between the two groups in terms of game skills and their understanding of projectile motion. Implications for educational stakeholders, parents and app designers are discussed along with future research directions.