What Molecules Make the Holes in Bread?

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In this activity, learners will discover why there are holes in bread. By mixing water, yeast and sugar, learners will see bubbles rise from the bottom of the tube as the yeast metabolizes the sugar into carbon dioxide and ethanol. When bread is made, the yeast metabolizes sugars from the flour and makes carbon dioxide bubbles. These bubbles make the dough rise, and are later seen as the holes in bread. [Activity is publicly available through a web crawler capture on Archive.org.]

Quick Guide

Preparation Time:
10 to 30 minutes

Learning Time:
30 to 45 minutes

Estimated Materials Cost:
$10 - $20 per group of students

Age Range:
Ages 8 - 18

Resource Types:
Activity, Experiment/Lab Activity


Materials List (per group of students)

  • container with sugar
  • container with yeast (use regular yeast, not rapid rise)
  • test tubes
  • flashlight
  • water bath (heated to 50 degrees Celsius)
  • squeeze bottle with water (inside the water bath)
  • test tube rack (inside the water bath)
  • slice of bread in Petri dish
  • 2 scoops
  • 1.5 min timer or stop watch


  • Life Sciences
    • Diversity of Life
      • Protists and Fungi
  • Physical Sciences
    • Chemistry
      • Chemical Reactions
      • Solutions
    • States of Matter
      • Solids
      • Liquids
      • Gases
      • Changes of Phase
    • Structure and Properties of Matter
      • Atomic Structure

Informal Categories

  • Food and Cooking


To use this activity, learners need to:

  • see
  • read
  • touch

Learning styles supported:

  • Involves teamwork and communication skills
  • Uses STEM to solve real-world problems
  • Involves hands-on or lab activities


Components that are part of this resource:

Access Rights:

  • Free access


Source Collection

  • Pfizer Foundation Biochemistry Discovery Lab


  • All rights reserved, New York Hall of Science, 2001

Funding Sources:

  • Pfizer Foundation
  • National Science Foundation, 9814954
  • The Camille and Henry Dreyfus Foundation, Inc.