Show the children the cup of water with coffee grounds. Explain that the grounds are the oxygen that is in the water they can not see. Then show them the kleenex tissue and share that this is the gills of a fish. Place the tissue over the top of the empty cup and slightly push it in to form a pouch. Explain that as a fish swims, the water flows through its gills (pour the water with coffee grounds into the cup)and the gills collects the air (grounds)from the water. Pull the tissue up and show the children the air (grounds) that the gills collected. Then show them the water that has no grounds or air. This is the water that the fish releases to reoxygenate.