Context-aware ubiquitous learning has been recognized as being a promising approach that enables students to interact with real-world learning targets with supports from the digital world. Several researchers have indicated the importance of providing learning guidance or hints to individual students during the context-aware ubiquitous learning process. In this study, an expert system-based guidance approach is proposed for conducting effective context-aware ubiquitous learning activities based on the domain knowledge provided by experienced teachers. To evaluate the effectiveness of the proposed approach, an experiment on a learning activity in a senior high school Geosciences course has been conducted. The experimental results show that, with this new approach, the students' learning achievements have been significantly improved in terms of several cognitive processes in Bloom's taxonomy of educational objectives, such as "analyzing" and "evaluating." Consequently, it is concluded that the context-aware ubiquitous learning system with the interactive guiding approach has benefited the students in enhancing their higher order thinking competences. (Contains 5 tables and 5 figures.)