Although Augmented Reality (AR) technology has already been adopted into mobile learning environments, additional effort must be put towards providing strong evidence that AR-based mobile systems are excellent educational tools that make a positive impact in or outside of the classroom. Our study utilized a similar AR-based mobile learning system developed to authentically teach a liberal arts course at a Taiwanese university. Under controlled study environments, we were able to design a system that could impart relevant concepts from the course to students outside of the traditional classroom setting. Experimental results demonstrated that students with the opportunity to learn through the proposed system demonstrated higher learning motivation, had better learning performance and comprehension abilities than those studying via the conventional outdoor instruction approach. Moreover, the questionnaire survey conducted after our study revealed that "confidence" was the most highly rated motivational factor among students who used the proposed system, suggesting that students were quite motivated to learn using the novel system supplemented with technological advances because they felt more sure of their knowledge and performance. Thus, we believe that using the proposed system can effectively improve the learning outcomes of students enrolled in the liberal arts course, with the particular benefit of boosting confidence in gaining new knowledge, which leads to an improvement of overall learning performance and motivation.