This discrepant event was created based on the book The Breadsisters of Sinking Creek

The Yeasties

Science Concept: Chemical Reaction

PA Science and Technology Standard(s): Provide clear explanations that account for observations and results


5 pouches of yeast

5 mystery foods

1. sugar

2. oil

3. flour,

  1. cookies
  2. control (water)

5 zip-lock bags

measuring cup (for water)

Set-Up: Be sure to have the exact amount of the mystery food in each bag measured beforehand to increase student involvement. Each bag should be labeled with letters A-E so there is no confusion.Have each bag lay flat on the table for the students to observe each food.


  1. Show each bag of mystery food
  2. Pour one pouch of yeast into Bag A.
  3. Pour one cup of water into Bag A.
  4. Close the bag and lay flat.
  5. Repeat steps 2 -4 with the remaining bags.
  6. Let bags stay still for 2 hours for the reaction to occur.
  7. Observer each bag to see which mystery food the yeast ate the most.
  8. The bag with the flour should be the one with the most reaction to the yeast.

Scientific Explanation:

This discrepant event deals with chemical reactions.A chemical reaction is a process that results when two chemical substances combine together.The substance originally involve in a chemical reaction at called reactants.Chemical reactions are typically associated with chemical changes. Chemical changes are defined as changes that yield one or more product that usually has properties different from the reactant. In this specific event, the yeast and the flour combine to make a gas called Carbon Dioxide.Also, bubbles appear in the solution.

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