This lesson investigates the phenomenon of bread dough rising. Natural phenomena are observable events that occur in the universe that we can use our science knowledge to explain or predict. Phenomenon-Based Episode: What makes bread dough rise? Disciplinary Core Ideas: Matter and Energy in Organisms and Ecosystems National Agricultural Literacy Outcome Theme: Culture, Society, Economy & Geography Phenemona Table- Food Science: Bread Dough Challenge

Activity 1: What makes bread dough rise?

1. Introduce yeast by passing around small Ziploc bags of yeast or displaying one at the front of the room. Ask students if they know what it is and what it is used for. If no one knows, explain that it is yeast and that our primary use for it is in cooking.
2. Provide a class demonstration of how yeast works using the following steps:
   1. Fill 3 quart or sandwich sized ziploc bags with 1 tablespoon of yeast per bag.
   2. Add 1 tablespoon of sugar to bag two and 3 tablespoons of sugar to bag three. (Bag 1 will serve as the control and will not have any sugar.)
   3. Place 1/2 cup of warm water in each bag and mix the contents thoroughly with your fingers.
   4. Push the air out of the bag and seal tightly.
   5. Place bags in a central area for observation.
3. While the yeast is rising, give each student one copy of the Food Science: Bread Dough Challenge handout and project the corresponding PowerPoint.
   • Tip: It will take approximately 20 minutes for the ziploc bags to fully inflate. However, exact time will vary depending on the temperature of your classroom. The next steps may be interchanged as needed for class flow.
4. Using PowerPoint slides 2-5, discuss the answers to the four questions contained on the first page of the handout.
5. Return to your observation of the ziploc bags. Discuss why the first bag did not inflate and why bags two and three did. Compare bags two and three. Did more sugar yield more expansion of the bag? If not, discuss possible reasons why.
   • Safety Note: Be sure to open the ziploc bags before they pop.
6. Using the second page of the handout, draw on students' prior knowledge and have them answer the questions about how various organisms obtain energy.

Three Dimensional Learning Proficiency: Crosscutting Concepts Students link different domains of science fields into a coherent and scientifically-based view of the world. Cause and Effect: Events have causes, sometimes simple, sometimes multifaceted. Deciphering causal relationships, and the mechanisms by which they are mediated, is a major activity of science and engineering.

Activity 2: Bread Dough Challenge

1. Ask students if they can name any food products that are made using yeast and alcoholic fermentation. Examples include bread, beer, and wine.
2. Tell students that one of the challenges to making bread (at home or on the industrial scale) is the time that it takes to allow the dough to rise. Food scientists use engineering, biology, and chemistry to evaluate and improve food products from the farm to the kitchen.
3. Tell students that they are on a team of food scientists at a bread company. They will be working together to discover the best recipe and preparation procedures to produce quick rising bread. To test as many variables as possible, the class will be divided into small groups.
4. Divide your class into 8-12 groups and assign each group one Bread Dough Challenge Variable. You can use any of the variables provided, or have students think of their own. Preselect the optional variables based on your class size and/or lab supplies available.
5. Explain to the class that one group will use the original recipe found in their Food Science: Bread Dough Challenge handout. This will serve as the experiment's "control." The remaining groups will change one variable and the remaining dough samples will be compared at the end.
   • Tip: As students determine their variables and how they will manipulate them for the experiment, allow them to pursue the wrong direction to provide an authentic learning experience and the opportunity to explain the outcome using science. For example, knowing that yeast needs sugar to grow, a student may greatly increase the amount of sugar in the recipe. If the yeast is not increased, this sample will not rise faster. It may not rise as much or even at all depending on the ratio. Refer to information about the molar concentration of sucrose for an explanation.
6. Provide lab supplies, answer student questions, and tell students where to take their dough once it is mixed. Have students fold their variable card in half to make a tent label to identify their dough.
7. Using a dry erase marker, have each group place a starting line on their jar at the level of the dough.
8. Allow at least 30 minutes for the bread dough to rise. Instruct students to place a second line at the level of the dough after 30 minutes.
9. Place all dough jars for students to observe. After observation time is over, allow students time to complete the last page of their handout which will contain their final recommendation to the bread company.

Help students avoid the misconception that yeast simply "grows" or becomes larger. Be sure they recognize what is happening on the cellular level which is budding, a form of asexual reproduction. Illustrate with a video.