| Biology demonstration manual |
Lesson: Les levures
Rationale: Show evidence of yeast respiration.
Materials: piece of bread
1. Show a piece of bread.
2. Explain that the holes are caused by the carbon dioxide given off by the yeast and then trapped in the bread dough before baking.
Source: Belin Sciences et Techniques Biologiques 6Ã¨me, p. 79.