Overwhelming popularity of Facebook as a social network site (SNS), especially among students, has shown growing interests of using it as a tool for education in and out of the classroom. However, despite concerted efforts from educationists, Facebook has hitherto unincorporated as a promising pedagogical tool. Influencing factors for such a use has already modeled structurally and validated, yet, the "increasing smart mobile usage to access Facebook" and its interactivity received insufficient attention in those models. Hence, our aim was to extend the existing structural model for two factors, namely mobility and interactivity. The structural equation modeling was applied to identify factors including mobility and its interactivity that may stimulate students to adopt Facebook for educational purposes. Online survey data were gathered from a sample of 510 undergraduate students using a structured and adapted questionnaire. Results of the present study revealed that in the extended model educational usage of Facebook was significantly related to its purpose and less significant to its adoption. Mobility was a significant factor in predicting the adoption in the extended model, even more than the social influence, while interactivity is significantly affecting the educational usage of Facebook. The extended model reconfirms the purpose of using Facebook is mainly for social relations. Similarly, community identification is the most significant factor for Facebook adoption and mobility seems to be further improving it. In conclusion, incorporating mobility and interactivity into the already existing model can better explain the pedagogical use of Facebook in the smart mobile age.