 Contextual interference has been shown to improve long-term learning among engineers in training of troubleshooting skills 15. Although well studied in sport and other areas outside healthcare, CI has been less well studied in medical education with only a few studies on surgical procedural tasks. Not all implementations of contextual interference have yielded better skill retention and transfer compared to blocked practice 16, 17. In this project, contextual interference will be carefully tested for BLS training by optimizing subtask transitions. In surgical procedures, for instance, CI studies have involved breaking a complex sequential task or procedure into subtasks and implementing CI practice with arbitrarily organized subtasks. An issue with that approach is that learners miss the opportunity to practice the transition from one subtask to another, which can hinder learning. Conversely, BLS skills stations are distinct from each other, technically simple, and do not require complex transitions between skills. 