International studies indicate that the use of smart mobile devices and their accompanying educational applications (apps) can revolutionize young children's learning experiences. Although there is a vast array of educational apps for preschoolers, they are not actually educational in their majority. In this context, it is important for preschool teachers to be able to assess each app for its effectiveness in educational practice. To evaluate educational mobile apps, this paper presents a rubric (abbreviated as REVEAC) in four areas: contents, design, functionality, and technical quality, each having multiple aspects. In this paper, we discuss the known problems in using educational apps and we present a review of relevant literature, as well as the process of formulating REVEAC. Finally, the paper concludes with a brief discussion of REVEAC limitations and future work.