the pandemic closure brings [4], [5]. This plan was a challenge to K-12 students from Public Schools: physical exercises in which the students could learn in a playful and experiential way a concept of Natural Sciences [6]. This challenge focused on building cognitive, socio-emotional, and behavioral skills, and on quality of life through the care of the physical health of educational actors [7].The chosen concept was the "center of mass" because it is a biometric, dynamic, and contextual variable linked to body movement -kinesiology [8], [9], where students could be experienced in the quarantine period ('lockdown') through physical exercises. Also, there is a significant probabilistic relationship between the more a child is physically active (spontaneous and induced sports practices), the more the child's ability to learn and solve problems (within the zone of proximal development) [10], [11].An Interactive Model ("Change your Center of Mass!") was built based on a mathematical model with the center of mass as a dependent variable and independent variables: body mass index and vertical jump, in which students and teachers could insert data, and qualify as your center of mass is: from regular (not very active physically) to excellent (in activity with high performance). And this interaction with the Model could be a motivating factor for the student to remain active during and after the pandemic.The center of mass is a hypothetical point where the whole mass converges as if all external forces were being applied at that point. The center of mass can coincide with the center of gravity when a human body is under the influence of a uniform gravitational field [8], [12], [13]. This biophysical variable is important because it is related to the student's biomechanics and biometrics, his body volume has a direct and proportional relationship with his movement, it can be quantified (e.g. body mass index on running speed) and qualified: the perceptual effort used to get out of inertia (e.g. laziness) [14].Jumping jacks is a physical exercise in which you can study and analyze the center of mass about its induced variation because it is a vertical movement in which, over time, we can verify a variation in the position of the center of mass in student (or athlete), if students are actives and change Abstract-The pandemic caused by Sars-CoV-2 resulted in a period of physical distance and school closures. This motivated us to elaborate on some physical and psychological harm reduction plan for the students. A challenge was proposed to K-12 students from Public Schools of the Recife City: physical exercises in which the students could learn playfully and experientially a concept of Natural Sciences. The chosen concept was the "center of mass" because it is a biometric, dynamic, and contextual variable linked to body movement, which could be experienced in the quarantine period. The objectives of this work were: (i) to propose a challenge through the physical exercise to K-12 students (jumping jacks), which implies the study...