Playing with balloons, water, oil, and bottles help put this lesson over the top! Participants use air-filled balloons in water tanks to experience gas compression. They also use oil-filled bottles to experiment with buoyancy. Included are detailed materials and procedures, helpful diagrams, a photo of the lab setup, and a plethora of critical-thinking questions. Make sure to fit this lesson into your biology class when studying adaptations or a physical science class when studying properties of fluids.