['Just-In-Time Learning is a concept increasingly applied to medical education, and its efficacy must be evaluated.', 'A 3-minute video on chest tube insertion was produced. Consenting participants were assigned to either the video group, which viewed the video on an Apple® iPod Touch immediately before chest tube insertion, or the control group, which received no instruction. Every participant filled out a questionnaire regarding prior chest tube experience. A trained clinician observed participants insert a chest tube on the TraumaMan® task simulator, and assessed performance using a 14-item skills checklist.', "Overall, 128 healthcare trainees participated, with 50% in the video group. Participants included residents (34.4%, n = 44), medical students (32.8%, n = 42), and U.S. Army Forward Surgical Team members (32.8%, n = 42). Sixty-nine percent of all participants responded that they had never placed a chest tube, but 7% had placed more than 20. Only 25% of the participants had previously used TraumaMan®. Subjects who viewed the video scored better on the skills checklist than the control group (11.09 ± 3.09 versus 7.17 ± 3.56, P < 0.001, Cohen's D = 1.16). Medical students (9.33 ± 2.65 versus 4.52 ± 3.64, P < 0.001), Forward Surgical Team members (10.07 ± 2.52 versus 8.57 ± 3.22, P < 0.001), anesthesia residents (8.25 ± 2.56 versus 5.9 ± 2.23, P = 0.017), and subjects who had placed fewer than 10 chest tubes (9.7 ± 3 versus 6.6 ± 3.9, P < 0.001) performed significantly better with the video."] Does use of mobile learning module improve skills in chest tube insertion?