This paper reports on an empirical research on the Interaction Equivalency Theorem posited by Anderson (2003a), consisting of the three elements of teacher-student-content interaction. Using an author-developed survey, the paper reports the priority order of interaction elements to assure learning quality with two parameters of learning modes and subject orientations. The inventory was tested in four universities with a total of 236 students. The results revealed that student-teacher interaction for face-to-face (F2F) and language-oriented course, and student-content for online and knowledge-oriented course were prioritized in students' perceptions to obtain higher satisfaction. In addition, the experience of increased asynchronous online written interaction with peers in the blended course design produced a change in the students' perceptions towards the necessary interaction elements. The research therefore adds empirical validity of the Theorem. Further research directions regarding the Theorem are also provided. (Contains 7 figures and 1 table.)