Introduction: Emergency department (ED) transthoracic echocardiography (TTE) is an important application of emergency department bedside ultrasound. Given limited curricular hours and economic constraints, training using ultrasound simulators represents an attractive alternative to using live-human models. Despite increased uptake of ultrasound simulator technology, educators lack evidence informing how best to use this technology. Three educational paradigms will be explored in this study: self-guided theory (learners are able to determine when they have had “enough practice”), desirable difficulties (manipulating practice conditions to create more durable and flexible learning), and the challenge point framework (avoiding cognitive overload). The question we seek to answer is: in novice medical trainees, which practice condition leads to improved learning in a test of retention when assessing the ability to generate and interpret a parasternal long axis (PLAX) and apical four-chamber view (A4CH) of the heart? Methods: Ultrasound-novices will be recruited from rotators in the ED. Participants will be allocated to one of three groups based on a 2x2 orthogonal design: Group A (variable difficulty × self-determined practice); Group B (variable difficulty × fixed practice); Group C (static difficulty × fixed practice). A standardized didactic lecture will be presented to each participant. Practice conditions with respect to difficulty level (easy, medium, hard) and structure of practice (learner-determined or fixed practice) will vary according to assigned groups. All groups will receive standardized feedback. The ability to identify anatomy and pathology will be assessed. At the conclusion of practice, a post-practice skills assessment and survey will be administered. Two to three weeks later, participants will be retested using three case scenarios. Screenshots of the participant-determined “best image” and video of the performance will be taken to be evaluated by two blinded (to group allocation) reviewers. Results: We have currently enrolled 14 participants. We aim to complete enrollment by April 2016. Conclusion: We anticipate that our study will provide evidence to inform the best use of ultrasound simulators for teaching TTE in the ED. It will also provide insight into the ability of three educational theories to predict best learning using a novel educational intervention.