Chemistry of Cooking

Classroom Activities

Activity One: Introduce the Unit with the Mentor Text

To introduce the unit on the chemistry of bread baking, students will learn about this common food enjoyed across many cultures and how each region or family makes their own versions. This unit is designed to be taught in conjunction with our district’s nutrition curriculum with a focus on how people in different cultures use different food sources to meet their nutritional needs. 

Materials: Everybody Bakes Bread, t-chart on chart paper with question, chart to track content from text (examples below), student science journals

Prepare T-Chart

Prepare text content chart

Begin by asking students the question posted on the chart, “How bread is made?” Record any answers and ideas on the left side titled “What We Know.” Read aloud Everybody Bakes Bread by Norah Dooley. The story follows the main character, Carrie, through her multicultural neighborhood.

On the 2^nd chart, track Carrie’s visits with her friends and neighbors and the types of breads that she samples: coconut bread from Barbados, chapatis from India, corn bread from South Carolina, pocket bread from Lebanon, challah from the Jewish culture, pupusa from El Salvador, and braided bread from Italy. The recipes for each of the breads are located at the end of the book.

Return to the t-chart of responses and on the right-side section titled “What We Have Learned.”

In their science journals, students should transfer the information from each completed chart. 

Activity Two: Balloon on a bottle

Part One: Activating Yeast with Sugar

As noted in the sections on yeasts and chemical leaveners, the purpose of any leavener is to produce the gas that makes bread rise. Yeast does this by feeding on the sugars in flour, and expelling carbon dioxide in the process. This experiment uses Saccharomyces cerevisiae, commonly known as baker's yeast, the most common yeast used in homemade breads. Show the students that yeast is tiny - just one gram holds about 25 billion cells and can generate a significant amount of carbon dioxide, as long as it has the simple sugars it uses as food. The yeast can use its own enzymes to break down more complex sugars, like the granulated sugar in this activity, into a form that it can consume.

Students will make a yeast-air balloon to get a better idea of what yeast can do.

Materials for each group of 4-5 students:

2 packets of active dry yeast

2 cups very warm water (105° F–115° F) 

2 tablespoons sugar

2 large rubber balloons

2 small (1-pint to 1-liter) empty water bottles

1. Stretch out the balloons by blowing them up a few times and then set aside. This step should be done by the teacher or another adult.
2. Pour a packet of yeast and the sugar into the cup of warm water.
3. Pour a packet of yeast only into the other cup of warm water.
4. Once the yeast and sugar have dissolved, pour that mixture into one of the bottles.
5. Pour the yeast and water into the other bottle.
6. The water will have begun bubbling as the yeast produces carbon dioxide. Attach the balloons to the mouths of the bottles, and set both aside. After several minutes, the balloon will stand upright as it inflates.

Students should write their observations in their science journals.  What is happening in each bottle? Why do you think there is a difference?

Explain to the students that as the yeast feeds on the sugar, it produces carbon dioxide. With no place to go but up, this gas slowly fills the balloon.  A very similar process happens as bread rises. Carbon dioxide from yeast fills thousands of balloon-like bubbles in the dough. Once the bread has baked, this is what gives the loaf its airy texture.

Part Two – Activating Baking Soda

Students will make a baking soda-air balloon to understand the chemical reaction that occurs.

This activity will demonstrate the power of gas produced when of baking soda and vinegar are mixed as the balloon is blown up by the gas created.

Materials for each group of 4-5 students:

4 ounces water

4 ounces vinegar

2 tablespoons baking soda

2 large rubber balloons

2 small (1-pint to 1-liter) empty water bottles

1. Using the funnel, add the baking soda to each balloon (two people will need to do this; one person to hold the balloon open and the other person to put the baking soda inside of the balloon).
2. Pour the vinegar into one bottle.
3. Pour the water into the other bottle.
4. Carefully fit the balloon over the bottle opening (be careful not to drop the baking soda into the vinegar yet).
5. Once the balloon is fitted snugly on the nozzle, hold up the balloon and allow the baking soda to fall into the vinegar or the water.
6. After several minutes, the balloon on the bottle with vinegar and baking soda will stand upright as it inflates.

Students should write their observations in their science journals.  What is happening in each bottle? Why do you think there is a difference?

Activity Three: Reading a recipe

Materials: a set of copies of the seven bread recipes for each student, highlighters, glue sticks or tape, student science journals, teacher selection of text examples: story (book), poem, non-fiction text

Students will learn the unique structure of a recipe as it compares to the structure of a story, non-fiction text or poem.  Show examples and discuss general features of each: several pages, characters, illustrations, etc. 

In the selection of the bread recipes from the mentor text, students will locate the two major sections of a recipe in each example – the list of ingredients and the process or procedure for making the product.  

Students will then locate the common ingredients in bread products and use these following color coding to indicate each component.

Flour – blue

Sugar – yellow

Yeast – green

Baking soda or baking powder – red

Eggs – orange

Liquid – purple

Other ingredients will remain unhighlighted, which will demonstrate the differences between the recipes, indicating cultural preferences and resources.  Completed work will be glued or taped into student journals.

Activity Four: Comparing Chemical Reactions

Part One:  Kneaded and Unkneaded Yeast Bread

Using the experience and information from Activity Two (activating yeast), students will learn how the carbon dioxide gas becomes trapped in the gluten sheets of bread that has been kneaded and stretched.  Bread that has not been will show different results.

Students, in three groups and with adult support, will prepare the following recipe:

2 cups warm water (110 degrees F/45 degrees C), 2/3 cup white sugar, 1 ½ tablespoons active dry yeast, 1 ½ teaspoons salt, ¼ cup vegetable oil, 6 cups bread flour

1. In a large bowl, dissolve the sugar in warm water, and then stir in yeast. Allow to proof until yeast resembles a creamy foam. Mix salt and oil into the yeast. Mix in flour one cup at a time.
2. Divide the dough in half. Place one half in a well-oiled bowl and turn to coat. Cover with a damp cloth. Be careful that the dough is not kneaded after mixing and sits until placed in the loaf pan in Step 4.
3. Knead the remaining dough on a lightly floured surface until smooth. Students may take turns with this part. Place in a well-oiled bowl, and turn dough to coat. Cover with a damp cloth. Allow to rise until doubled in bulk, about 1 hour. Punch dough down. Knead for a few minutes.
4. Shape dough into loaves, and place into two well-oiled 9x5 inch loaf pans. Allow to rise for 30 minutes, or until dough has risen 1 inch above pans. Bake at 350 degrees F (175 degrees C) for 30 minutes.

Students will observe similarities and differences and document their learning in their journals.  Once bread has cooled, students can feel, smell, and taste samples of each loaf.  Questions for students to consider in their writing:  What seems the same? Different? What do you prefer and why? What happened in each loaf and why?

Part Two:  Leavened and Unleavened Cornbread

Baking powder acts immediately upon addition of water. As soon as the powder gets wet, the two chemicals begin to dissolve and react with each other to produce carbon dioxide.  In our quick bread recipes, we don’t want the baking powder to release all its gas as soon as we mix the batter, before it is baked enough to trap the CO₂ bubbles in place.  This experiment demonstrates the what happens when the CO₂ escapes before baking.

Students will work in four groups.  Each group will prepare the following recipe:

1 cup all-purpose flour, 1 cup yellow cornmeal, 2/3 cup white sugar, 1 teaspoon salt, 3 ½ teaspoons baking powder, 1 egg, 1 cup milk, 1/3 cup vegetable oil

Preheat oven to 400 degrees F (200 degrees C). Spray or lightly grease one 9-inch round cake pan for each group.

Groups 1 & 2 will gently stir the ingredients.

In a large bowl, combine flour, cornmeal, sugar, salt and baking powder. Stir in egg, milk and vegetable oil until well combined. Pour batter into prepared pan.

Bake in preheated oven for 20 to 25 minutes, or until a toothpick inserted into the center of the loaf comes out clean.

Groups 3 & 4 will mix with an electric mixer

In a large bowl, combine flour, cornmeal, sugar, salt and baking powder. Add in egg, milk and vegetable oil and mix thoroughly for 1 minute. Pour batter into prepared pan.

Bake in preheated oven for 20 to 25 minutes, or until a toothpick inserted into the center of the loaf comes out clean.

Students will observe similarities and differences and document their learning in their journals.  Once bread has cooled, students can feel, smell, and taste samples of each loaf.  Questions for students to consider in their writing:  What seems the same? Different? What do you prefer and why? What happened in each loaf and why?

Activity Five: Visit a bakery

Students will enjoy a trip to one of our local New Haven bread bakers – Lupi Marchigiano Bakery or Apicella’s Bakery.  Both bakeries have long histories as family-owned businesses and offer opportunities to learn about “how bread is made.”

Activity Six: Host a bake sale

Students and their families will bake a favorite recipe or two to include in our classroom bake sale to be held during school lunch time.  The students will be able to share their learning with students from all grades.  All of the recipes of the baked goods sold at the bake sale will be compiled into our own cultural recipe book. Families may include stories or the history of the recipes in their write-ups.