The current study will be conducted in the Clinical skill and simulation center of the College of Medicine, Dar Al Uloom University, Riyadh, Saudi Arabia. Students will be informed that participation was anonymous, voluntary, and this intervention will be an extracurricular activity that will not count to their actual grades.

Participants To reduce performance bias, a group of 40 third-year medical students (academic year 2020-2021) will randomly assigned to flipped or traditional learning sessions. These students had already completed the Cardiovascular block in the second semester of their second year. The cardiovascular block (6 credit hours, 6 weeks) contents handle all the subjects related to cardiovascular system from the view of the basic medical sciences such as anatomy, physiology, biochemistry, microbiology and pathology, and pharmacology. Besides, clinical medical sciences integrated in this block as clinical skill sessions that run synchronously with the lectures and focus on the application of relevant medical practice using clinical skills and simulation center. They took a total of three sessions in the block, each running for 2 hours.

To ensure that each student has an equal chance of getting exposed to any of the teaching approaches used in our study, the students will be randomized into interventional and control groups. The attendance registers of all third-year students will be considered, from which every third student will be selected making a total of 40. Out of these the first 20 formed the intervention group and the second 20 were considered as the control group. To avoid the Hawthorne effect (change of the participants' behavior in response to their awareness of being observed), the students will be blinded to their groups and will be unaware of when and what will be assessed throughout the skill lab sessions \[1\]. Notably, both control and interventional groups will be supervised by the same medical teachers, have the same scenario, and same simulated patients. They will finally evaluated by the same instructors based on a well-structured checklist.

Preparation of flipped classroom materials Three instructors worked to prepare the study materials, for the application of the flipped classroom teaching methodology in the clinical skill and simulation center for the preclinical students. The learning objectives of the cardiovascular clinical case were identified. We gathered the following relevant, high-quality videos from YouTube: Cardiovascular History Taking Key Symptoms OSCE Guide, Cardiovascular Examination - OSCE Guide, Heart murmur sounds, and Blood pressure measurement - OSCE guide. Moreover, short PowerPoint presentations including teaching materials (investigations and treatment) and pertinent to the clinical case were created and saved as videos. Of note, all included videos are shorter than 10 minutes in duration. All these materials were uploaded into the freely accessible EdPuzzle software to embed our own questions at appropriate places in the videos. The EdPuzzle platform helped to assign these videos to a group of students and get hassle-free analytics: see who watched the video, who didn't understand the lesson and who did a good job. Students can re-watch the video as many times as they need at their own pace, while we can easily check their progress from our account. Reports of student answers will be prepared by teacher prior to face-to-face session, and logs of the students' interaction with the videos will be monitored by the teacher.