You will need:
An aquatic plant (such as waterweed),
Baking soda dissolved in water (5 grams per liter),
A glass funnel, test tube and beaker,
A match and a lamp.
Instructions:
Place the aquatic plant in the beaker, then put the funnel over it.
Fill the beaker with the baking soda solution.
Then, place a test tube over the funnel.
Make sure the aquatic plant has contact with the baking soda solution.
When the test tube has no water left, light a match and put it in the test tube.
The match should extinguish due to there being too much oxygen.