Constructivism learning theory emphasizes the importance of collaborations in creating a shared understanding. In the given study, collaborations facilitated on a mobile SMS based Twitter platform as an effort to design mobile-based guided-informal learning. The objectives of the study were i) designing m-learning contents for Twitter, ii) facilitating collaborative m-Learning, and iii) testing effectiveness of mLearning tool. A mobile learning approach (mLA) was designed in collaboration with users, following design-based research theories. Data were collected using participatory methods, questionnaires, and logged data in the mLA. Descriptive methods, network analysis methods and mean comparisons used in the data analysis. Members of a young farmer club in Kandy, Sri Lanka participated in the research process for two years.Pedagogical tools, such as lessons, interactions, assessments and feedback, designed to match with Twitter functionalities and features. Participation in the mLA has improved knowledge in learners, and has created collaborative learning opportunities. Learners were generally satisfied with mLA as a guided-informal learning tool. The drawbacks were mainly due to technical problems, and limitations in the SMS based platform, which has limited opportunities to acquire higher order learning skills. Future implementations of the mLA model need to focus on designing mobile based applications for Smartphones in creating more collaborative and interactive learning spaces.