With the recent advances in learning technologies, researchers are exploring the benefits of touch-based applications to reinforce handwriting skills in children with writing difficulties. One of the reasons for writing difficulties is the lack of fine motor skills. Hence, an Android application was developed for children with writing difficulties to enhance their hand dexterity. It has six activities for improving hand-eye coordination, spatial organisation, and pencil/pen grip in children. The design of all these activities is based on the oscillation theory of handwriting. This paper explains the usability evaluation of this Android app and how improvements have been made in the application based on the user feedback. Ten participants have evaluated the initial prototypes in five iterations and the final product was built by considering their feedback. The study shows that the user evaluation approach is effective in identifying the usability issues and in improving the user interfaces and also the functionalities of the software application. From our experience, we suggest that including user researchers and ET researchers along with children in the usability evaluation process is beneficial, especially when the educational software users are children below 15 years of age.