Effective instruction starts with an understanding of the learner’s pre-existing knowledge (Bransford, Brown, & Cocking, 2000). That being said, online instruction often involves inflexible content presented the same way to each student regardless of their current level of understanding (van Rosmalen, Vogten, van Es, Passier, & Poelmans, 2006).The shortcomings of static instruction are intensified in online high school learning because online learning is often used for remediation and credit recovery for students that have not been successful in their traditional class (Queen & Lewis, 2011). Learning progressions, which are research-based, testable models of how learners develop their understanding of a concept over time (National Research Council (NRC), 2007), offer a model of student thinking that can lead to online instruction that accounts for the learner’s thinking. The purpose of this design-based research study is to use a two-phase, sequential mixed methods (Creswell, 2009) approach to investigate the use of a learning progression to inform the specific instruction delivered in an online high school physics unit on waves. No significant difference in learning outcomes were found between the students that participated in the waves LP based unit and those that participated in the comparison unit. Statistically significant differences in how the participants evaluated the units were found. In addition, the design based research processed followed resulted in a refinement of the waves learning progression and the online unit based on the progression.