The student conducted an experiment using a plastic cup filled with water, cardboard, and sunlight to test if zero gravity could be created. They found that when the cup was inverted with cardboard placed on top, the cardboard remained in place due to the lack of air bubbles and gravity within the fully submerged cup. The student concluded that zero gravity can be achieved and learned this principle allows floating, but still wonders why people sink in the ocean if they can float in other water.