After the learning activity, ANCOVA was used to compare the post-questionnaire ratings of the students’ self-efficacy by excluding the impacts of the pre-questionnaire ratings. Table 2 shows the ANCOVA result. The adjusted means of experimental group A, experimental group B, and the control group were 3.60, 3.67, and 3.27, respectively. Moreover, it was found that the three groups had significant differences on the self-efficacy ratings, with F = 3.67 (p < .05). The pairwise comparisons further showed that both experimental groups A and B outperformed the control group, implying that both DGBL and digital instructional materials on e-books could significantly improve the students’ self-efficacy in comparison with the traditional instruction model.