Sunday Funday, Playdates, Open Gym and more! Open gym is a great time for your kid to come in and explore the KIDZ GYM environment outside of classes. Whether they need to ease in to the new space by coming to open gym or maybe have a fun day out with their grandparents, KIDZ GYM Open Gym is a great time for them to explore uninterrupted. Balance on our balance beams, complete the obstacle course of the day, jump on the trampoline, and learn at your own pace.