4th – 6th grades
Difficulty of Project
Less than $5.00
This investigation uses latex balloons. Be aware of any allergy issues. Also to prevent choking, keep the balloons away from young children. Wash hands after any experiment using yeast.
Readily available or easily purchased from the grocery store
Approximate Time Required to Complete the Project
One hour to complete the investigation and collect the data; one day to prepare the science fair display.
To investigate yeast fermentation and its results
- 2 empty plastic 16-ounce water bottles
- 2 packages of active dry yeast
- 2 latex balloons
- 2 tablespoons of sugar
- Masking tape
- Measuring spoons
Yeast is an ingredient used to make baked goods rise. Yeast is a live microorganism. When yeast feeds on sugars, such as in bread, it ferments. Fermentation produces carbon dioxide. Carbon dioxide is a gas that expands.
In this experiment the carbon dioxide that is released when the yeast and sugar combine inflates the balloon.
fermentation: the chemical reaction of yeast and sugar to carbon dioxide
microorganism: an organism that is too small to be seen by the eye alone
Fermentation is the process that happens when sugar is added to yeast. Fermentation produces carbon dioxide.
- How does yeast make bread rise?
- What happens when sugar is added to yeast?
- Gather the necessary materials.
- Using the masking tape, label one bottle “Yeast and Sugar” and the other bottle “Yeast Alone.”
- Pour 1 cup of warm water into bottle.
- Add on package of yeast to each bottle.
- In the bottle labeled “Yeast and Sugar,” add two tablespoons of sugar.
- Gently shake both bottles until the yeast has dissolved.
- Place a balloon over the opening of each bottle and tape the balloons in place.
- Observe the bottles for 30 minutes. Record any changes.
“Explaining Yeast to Kids” by Frederick Foodie at http://www.frederickfoodie.com/2009/10/explaining-yeast-to-kids.html