Reflection plays a very important role in learning processes and is very helpful for promoting learning performance. Many higher education institutions today are actively promoting learners' reflection ability in order to help them cope with the fast changing world they will be entering when they graduate. Online learning provides potential for applying new teaching and learning strategies. However, it has not yet been systematically studied how to concretely apply reflection strategies in an online learning environment. The aim of this study is to explore how high level prompts and peer assessment can affect a learner's reflection levels in an online learning context. The participants were 157 university students and each individual was randomly assigned to one of the fourteen learning conditions. We found that the main factor affecting reflection levels is high level prompts followed by high quality observation that has a moderating effect on learners' reflection levels. However, peer feedback has no significant influence on reflection levels. (Contains 7 tables and 5 figures.)