novelty. Moreover, short-term projects may adapt poorly to regular classroom practices that may last for several months. Another issue related to teaching duration is the closeness of the integration between mobile devices and the curriculum.
Most of the short programs included in our study involved only one or two units of teaching materials in the curriculum of a whole semester. Although it is not necessary for a teacher to use mobile devices in every class, different units or topics may
involve different instructional designs when such devices are being used, and hence an iterative trial process is likely to be needed to determine the optimal procedure for the best effects. Therefore, an abundance of mobile learning units will help to
provide exemplar models for teachers and enhance the possibility of transferring practices to different lessons. Furthermore, in terms of research, it can improve the reliability and ecological validity of mobile programs in education. Based on the above
considerations, researchers may consider appropriate intervention durations according to the skills or teaching methods to be developed with mobile devices. For example, for vocabulary-learning, bite-size materials and short-term durations may be appropriate for learners, but for more complex skills or methods such as inquiry or cooperative learning, longer interventions may be needed to warrant the effect of mobile programs.