The purpose of this study was to test the effects of two metacognitive scaffolds on learners' cognition by evaluating student critical thinking skills performance in an asynchronous discussion board and achievement in a blended learning module. The two scaffolds included a systematic protocol for individualized facilitation prompts and an analytic rubric with three criteria (critical thinking, participation frequency, and writing quality) along with four levels of achievement for each criterion. This research study employed a quasi-experimental, two-by-two factorial design. The study participants (N = 257) were assigned to one of four different conditions. Those provided with the rubric scaffold demonstrated significant differences with respect to their performances. However, the combination of both metacognitive scaffolds had a detrimental effect on learner performance. Additionally, learners reported higher satisfaction levels with the module when presented only with the rubric scaffold. Based on these results, the implications are discussed for those who design, facilitate, and manage asynchronous discussions and blended learning environments.