To echo the United Nations formulated Sustainable Development Goals (SDGs), SDG 4 is to ensure inclusive and equitable quality education and promote lifelong learning opportunities for all. Furthermore, high-quality education is the base on which human lives can be improved and sustainable development can be accomplished. Therefore, the affective emotional tutoring system established in this study enables learning via mobile devices, which are indispensable in daily life. The real-time interactive agent in the system guides learners to turn negative emotions into positive ones. We explored the usability of and user satisfaction with the affective emotional tutoring system. Sixty-two students participated in the study which used a quantitative research design to explore a learning situation. The overall usability of the system was evaluated with the System Usability Scale (SUS), and the Questionnaire for User Interaction Satisfaction (QUIS) was used to evaluate user satisfaction with the different elements of the system. The results showed that both the usability of and satisfaction with the affective emotional tutoring system were high. The emotional feedback mechanism of the system can help learners turn negative emotions into positive ones. Full article
