Nowadays, mobile device use among young children is on the rise. A kid using a smartphone or a tablet is a common sight today. This has been triggered by the worldwide advancement of mobile culture & technology. As a result, the number of mobile applications targeting the young children has tremendously increased. Studies, however, reveal that most of the applications are far from perfect. They are less learnable and hardly usable by the young children, as they do not match their mental models. Usability and learnability issues usually have a profound impact on the success of a mobile application. Nevertheless, there has been limited research on these issues for mobile applications designed for children. In regard to this, this paper aims to bridge the gap by reviewing usability guidelines suitable for designing 'near perfect' children mobile applications. We then propose a learnability model to help mobile developers and evaluators in designing and evaluating mobile application for this target population (5-10 year olds). Our discussion concludes that, though there are many mobile applications designed for young children, for any app to stand out and be successful, it needs to be designed with different technological skills, learning capacities and preferences tailored to young children