Subject: Physical Science
Grade Level: 5th Grade
Class Dates: One class period
Overview: Fermentation is a process carried out in living cells in order to obtain energy from carbohydrates without oxygen. In bread making, a microorganism called yeast is involved. The yeast converts glucose to carbon dioxide and ethanol, according to the following equation: glucose → ethanol + carbon dioxide. During the bread-making process, the carbon dioxide created by the yeast causes the dough to rise.
Objectives: In this activity, the class will work together to create one medium-sized loaf of bread (or could work in smaller groups if multiple cookers are available). Students will learn firsthand about the concept of fermentation, the specific chemical reaction that occurs when yeast ferments, as well as the various ways its products can be used.
Materials:
• Electric Crock-Pot or bread maker
• Mixing bowl
• 290 ml warm water
• 3 cups plain flour
• 2 teaspoons dried yeast
• 2 tablespoons milk
• 2 tablespoons sugar
• 2 tablespoons oil
• 1 1/2 teaspoons salt
Activities:
Instruct students to copy down the following directions before walking them through the steps:
• Grease the inside of the Crock-Pot.
• Mix all ingredients together in the mixing bowl.
• Remove the finished dough and knead it for 5 minutes.
• Allow the dough to rest for 10 minutes. (It should start to rise during this time.)
• Place the dough inside the Crock-Pot and cook on the highest setting for around 2 hours or until golden brown.
Evaluation:
Upon completion of the lesson, ask the students the following questions:
1. What caused the bread dough to rise?
2. What is the word equation for the fermentation reaction (involving yeast and sugar) that occurs in bread making?
3. If ethanol is one of the products of yeast fermentation, why isn't bread alcoholic?
Adaptations:
• A Crock-Pot or bread-making machine is ideal for use in this lesson, but if neither is available, the dough can be prepared in the classroom and then baked in a conventional oven.
• Students could use the recipe to make two batches of bread at home. They could also determine the cooking time needed for a large loaf compared to the time required to make a batch of small rolls.
• Investigations could also be made into the benefits of using fresh yeast versus dried yeast.
• A lesson where students research the history of alcohol production and bread making may be helpful in furthering their understanding of the fermentation process.
Lab Safety Guidelines:
1. Use caution: No horseplay, practical jokes, or pranks are
allowed in the science classroom.
2. Follow all instructions carefully, and ask your teacher
if you do not understand something.
3. Do not touch any equipment until instructed to do so.
4. Do not eat, drink, chew gum, or taste anything in the
science classroom.
5. Wash your hands with soap and water before entering and
leaving class.
6. Wear safety goggles when instructed.
7. Keep work area neat and clean. Remove all unnecessary
materials.
8. Clean work area and equipment when you're finished with
the experiment. Dispose of all waste properly.
9. Tell your teacher about any accident immediately.
10. Most chemicals used in the science room are dangerous.
Do not touch or smell any chemicals unless told to do so.
11. Students are not allowed to enter any storage closet at
any time.
12. Do not remove any supplies from the science classroom
without your teacher’s permission.
13. Use care when handling glassware. Never pick up broken
or hot glassware with your bare hands.
14. Use extreme caution when using matches, burners, or hot
plates. Only light burners when told to do so by your teacher, and do not put
anything into a flame unless specifically instructed to do so. Do not leave lit
burners unattended.
15. Dress properly: Long hair must be tied back, and no
dangling sleeves or jewelry is allowed. Wear closed-toe and heeled shoes. Wear
lab aprons as instructed.
16. Memorize the location of all safety equipment and
emergency exits.
Adapted from middleschoolscience.com.
