Guided inquiry is an active learning technique featuring collaborative group learning with a structured set of models and highly structured questions for students to discuss and answer. Moving this technique to an online delivery format presents challenges, leading to questions about the effectiveness of this technique during online instruction. This study looked at the synchronous online delivery of a sliding filament theory guided inquiry activity (Brown 2015) and scores on related exam questions in anatomy classes at Salt Lake Community College. Students who participated in the guided inquiry activity had a median score of 79% on questions related to the sliding filament theory of muscle contraction while those that did not participate in guided inquiry had a median score of 61%, revealing a medium effect on student test scores. This suggests that the guided inquiry activity was successful at improving student understanding and retention when delivered in the online teaching environment.