Talk with the students about using yeast in a recipe and how you would know what temperature of liquid to try and add to yeast for the best results. Organize left to right for cold, warm and hot water - or label. Swish gently back and forth to mix a little. Go back and observe and describe again and then make hypothesis regarding the use of yeast and appropriate water temperature in baking. This works best if you have at least 10-15 minutes to let the reaction happen before making final observtions.
Yeast catalyzes the breakdown of hydrogen peroxide into oxygen and water.
You will also be able to feel the heat released in the reaction through the sides of the film container. In this case look for color change. Use eyedroppers to do this. Explain about acids and bases being opposites. Tell them that vinegar is an acid and baking soda is a base.