With the explosion of mobile technologies, mobile teaching and learning became an important educational challenge. Since both teachers and students are increasingly using mobile devices in their everyday life, the question is why so little progress has been made in this direction. Clearly, the initiative of introducing mobile technology in class should come from teachers. Existing research shows a large diversity of factors that are influencing their perception as regards the usefulness and opportunity of mobile teaching and learning. This research aims to understand the extent to which the expectancy of increased students’ motivation and better understanding are influencing the perception of mobile teaching usefulness. A structural model has been developed and tested on two samples of science education teachers, one from Romania and the other from Lithuania. The results show that the expectancy of a better understanding of lessons by students has an important effect on the teachers’ perception of mobile teaching and learning.