Materials:
1 packet of active dry yeast
1 cup of warm water
2 tablespoons of sugar
1 balloon
1 empty water bottle
Directions:
Mix water, sugar and yeast in the bottle and place the balloon on top.
Encourage students to set
up several experiments using different combinations. Try cold water.
Try no sugar.
Label each and record your results.
Observe what happens. 
Questions for students:
Do you think the yeast is alive?
Will the same thing happen if we leave out the sugar?
Why does the yeast need sugar?
What is the gas inside the balloon?
Why is yeast used when baking bread?
Have students examine a piece of bread. Record Observations.
Teacher Background Information:
The purpose of any leavening agent is to produce gas that makes
the bread rise. Yeast feeds on sugars
and releases carbon dioxide in the process.
Yeast is tiny! Just one gram
holds about 25 billion cells! That
amount of fungi can produce a significant amount of carbon dioxide provided it
has simple sugars to use as food. As the
yeast feeds on the sugar and produces carbon dioxide, the balloon fills up with
this gas. A similar process happens as bread
rises. Carbon dioxide from the yeast
creates bubbles in the dough. Once the
bread has baked, this will give the loaf an airy texture.
Science and Engineering Practices
Planning and Carrying Out an Investigation
Constructing Explanations
Crosscutting Concepts
Cause and Effect
Stability and Change
Scale, Proportion and Quantity
Disciplinary Core Ideas
LS1 From Molecules to Organisms: Structure and Function
LS2 Ecosystems: Interactions, energy and dynamics
Below for you a printable for reading informational text.
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