The Bubbles in Bread
- Chemistry
- Ages 6–8 · Grades 1–2
- Hands-on experiment
What you’ll find out
- Yeast is made of tiny living things that turn sugar into a gas.
- The gas makes bubbles, which is why bread rises and is full of holes.
- A fair test changes only one thing at a time.
No sign-up and no real names. In the lesson you check your understanding as you read, run the experiment yourself, and practise until it sticks.
Yeast makes a gas
Bread is soft and full of tiny holes because of yeast. Yeast is made of tiny living things. Give it sugar and warm water and it makes bubbles of gas. Stretch a balloon over the bottle and the gas slowly blows it up. In dough, that gas makes the bread rise.
A fair test
What does yeast need? Set up three bottles and change only one thing each time. With warm water and sugar, the balloon grows big. With cold water and sugar, it barely grows. With warm water and no sugar, almost nothing happens. Yeast needs warmth and food.
Curriculum links: NGSS 2-PS1-4 · NGSS 5-PS1-4