My dad taught us about air. The water in our fish tank has a good amount of oxygen. Pollution and heat get rid of oxygen in water. When the water has shade, and when the water is cold , it has more oxygen. Fish and plants work together to stay alive.
Fish give plants carbon dioxide ,and the plants give fish oxygen.
He used two ways to measure the oxygen. He used chemicals and a machine. We learned that heat and pollution can take the oxygen out of water. Fish and people breath oxygen and breath out carbon dioxide. The date was November 9, 1999.