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Lesson Plan

Chemistry of baking yeast cake

Summary: 
Experiments with yeast, then baking soda and vinegar show how gas is made while amish bread is made, and how they make the holes in the cake.
Science content (2016 curriculum): 
Chemistry: States of Matter, Properties of Materials (K-7)
Chemistry: Chemical Changes (2, 7)
Curriculum connection (2005 science topic): 
Physical Science: Chemistry (grade 7)
Procedure: 

What is in the starter mix that we used for the Amish bread/yeast cake?
Today we will investigate the living things that are in here, and what they do.

What living things could be in there? They must be small...
Living things in this starter are yeast and bacteria.
(There are some kinds of yeast and bacteria that make you sick, but there are plenty that are helpful to us, and these ones are helpful yeast and bacteria).
The yeast and bacteria in here live well together, and stop other yeasts or bacteria from growing.

Activity to determine the role of the yeast in the starter mixture.

Activity to determine the role of the bacteria in the starter mixture.

The Amish recipe is a secret, because we do not know what kind of yeast and what kind of bacteria are in this starter mixture. But we do know that it has a yeast and a Lactobacillus bacteria.
Sourdough bread is the same - it has a yeast and a bacteria, both making the holes in sourdough bread.

Notes: 

A little much information for grade 2/3 class. Suggest either missing out the molecule models explaining what is going on (the yeast starts bubbling rapidly, so don't need much time waiting for it). Or just do one of the activities.

Grades tested: 
Gr 2
Gr 3
Teacher: 
Ingrid
Julie Johnson
Site tested: 
General Gordon Elementary