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Activity

Bread

Summary: 
Make bread and discuss the chemistry of it rising.
Science content (2016 curriculum): 
Biology: Features, Adaptations of Living Things (K, 1, 3, 7)
Chemistry: States of Matter, Properties of Materials (K-7)
Chemistry: Atoms, Molecules (3-7)
Chemistry: Chemical Changes (2, 7)
Materials: 
  • kettle of boiling water
  • a sink
  • an oven at 350 degrees F

Per group of 3 or 4:

  • bowl
  • spoon
  • warm water (1/3 cup) - teacher can add
  • dry yeast (1 tspn) in container and tspn measure
  • Sugar (1/2 tspn) in container and 1/2 tspn measure
  • Salt (1/4 tspn) in container and 1/4 tspn measure
  • Flour (1 cup) in container and cup measure
  • Vegetable oil (1 tbspn) - teacher can add

Per student:

  • square of aluminium foil

For teacher:

  • marker to write names on foil
  • beaten egg in tub
  • brush
  • baking trays
  • oven glove
Procedure: 

For a lesson on states of matter, the students pointed out every time they found a different state during this activity, whether it is one of the ingredients or a new state made by a chemical reaction.

Make dough in groups of 3 or 4.
Teacher adds water to the bowl. Students add yeast, sugar and mix.
The yeast is a living thing and starts to eat the sugar.
Students add the salt, flour and mix.
Then use hands to knead the dough (stretch, fold and flatten, repeated).

Divide each dough ball into 3 or 4 pieces. Put a piece on each square of aluminum foil for each student.
The students knead some more, then mould into a shape (e.g. pretzel).

Talk about what is happening to the flour as it is kneaded: the flour has molecules in it that are made longer and longer as the dough is stretched, then folded over. They give the dough an elastic texture, that gives the finished bread the light texture.

Leave to rise for a few minutes - a gas is made by the ingredients that make the dough rise.
(During the wait another activity can be run. To isolate the ingredients that make gas do Yeast eats sugar and makes gas or test which ingredients make gas. To look at the chemistry that makes the bread rise, use molecule models to model the chemical reaction. See lesson plans for integrating the activities)

Review ingredients/chemical reaction of the bread rising:
What is yeast? A living thing. Breathes like us.
It eats sugar and releases gas bubbles into the dough.
The gas bubbles get stuck in the dough and makes it rise.

Put the bread in the oven:
Add name to each piece of foil.
Brush bread with egg and put in the preheated oven.
Bake at 350 degrees F for about 15 minutes, until brown on top. They may need turning/switching around in the oven.

While waiting for the bread to bake do another activity: make butter or use molecule models to show the chemical reaction happening between yeast and sugar. See the lesson plans for including these activities.

Before eating the bread, break it open to see the holes in it, made by the expanded gas bubbles in the dough.

Attached documents: 
Notes: 

Yeast is not a plant, but a fungus. This was the closest curriculum connection that might incorporate a detailed yeast study.

Grades taught: 
Gr K
Gr 1
Gr 2
Gr 3
Gr 4
Gr 5
Gr 6
Gr 7
Teacher: 
Alane Lublow
Barbara Duncan
Carl Atterton
Christy Wong
Heather Wallace
Ingrid
Kecia Boecking
Patricia Ellis
Scott Malin
Sharon Ghuman
Sonia Ko
Sonja Watson
Teaching site: 
Brownies
General Gordon Elementary Science Club
ingridscience afterschool
JEMZ+ After school science
McBride Elementary
Laurier Elementary
ProD for Elementary teachers
After School Program at Elementary schools in New York City
Tyee Elementary
Activity originally developed and delivered: 

Science Development Programs Inc, New York.