This study explored the effects of directed and undirected online peer feedback types on students' peer feedback performance, argumentative essay writing skills, and acquisition of domain-specific knowledge. The study used a pre-test and post-test design with four conditions (feedback, feedforward, a combination of feedback and feedforward, and undirected feedback). In this exploratory study, 221 undergraduate students, who were randomly assigned to dyads, engaged in discussions about the pros and cons of "Genetically Modified Organisms (GMOs)", provided feedback to peers, and wrote an argumentative essay regarding the topic. Results indicated significant differences among the conditions in terms of the quality of provided feedback. This implies that the peer feedback quality can be enhanced or diminished depending on its type. Results also revealed a significant improvement in students' argumentative essay performance and domain-specific knowledge acquisition without significant differences among conditions. We discuss how the such increase in the quality of essays and learning outcomes might be related to the power of peer feedback regardless of the feedback type. We also discuss why using multiple instructional scaffolds may result in over-scripting that may diminish the power of peer feedback and the effects of the scaffolds themselves in online learning environments.