We conducted an experiment to test how much oxygen is in the air.
When you light a candle in open air it will last for quite awhile, that's because it has lots of oxygen to feed off. When we put the jar over the lit candle it only has 20% of oxygen accessible, so it slowly started using up all the oxygen in the jar. When the candle has used up all the oxygen the candle went out that's because there is no more oxygen to keep it burning. Because we put the jar slightly over the teaspoon it left a little jap for the water to rush in and replace the 20% space that the oxygen was. The space is quickly replaced with water. if you looked closely at the experiment you would see that the water is slowly rising inside the jar that's because it is slowly replacing the oxygen.