The "Direct-instruction Model" favors the use of teacher explanations and modeling combined with student practice and feedback to teach thinking skills. Using this paradigm, this study incorporates e-learning during an 18-week experimental instruction period that includes 48 preservice teachers. The instructional design in this study emphasizes scaffolding, observational learning, mastery of critical-thinking skills, guided practices, cooperative learning, providing feedback, self-reflection, online discussions, and active participation in an online learning community. This study employs 2 critical-thinking tests, 2 inventories, and 1 open-ended reflection questionnaire; and students' scores on the pretest and posttest are compared via the Repeated Measure Analysis of Variance. The primary findings are as follows: (a) all participants preferred the instructional design in this study; (b) the experimental instruction effectively improved the preservice teachers' critical-thinking ability as well as their professional knowledge and personal teaching efficacy concerning critical-thinking instruction; (c) the mechanisms contributing to the effectiveness of the experimental instruction mainly included discussing and sharing, observational learning, self-reflection, guided practice, and the learning community.