Tiny living things
Microbes are too small to see, but they are almost everywhere. Some help us and some can make us ill. With a yeast balloon experiment.
Read
Microbes are tiny living things. They are so small that you cannot see them with your eyes alone.[1]
There are three big groups of microbes: bacteria, viruses and fungi. They come in lots of shapes and sizes.[1]
Microbes are found almost everywhere on Earth. Some even help to keep us healthy.[1][2]
Many microbes are useful. A fungus called yeast makes bread dough rise. Microbes also help to make yoghurt and cheese.[2][5]
A few microbes are harmful and can make us ill. Washing your hands with soap helps to stop them spreading.[1][3][8]
Try it: The yeast balloon
You need
- Two small clean plastic bottles
- Two balloons
- A packet of dried baker's yeast
- Sugar
- Warm (not hot) tap water and cold tap water
- A funnel and a teaspoon
Safety
Use warm tap water only, never hot or boiling water. Do not taste the mixture. Wash hands after the experiment. Anyone with a latex allergy uses latex-free balloons or watches. Pour the mixture down the sink at the end.
What to do
- The teacher puts one teaspoon of yeast and one teaspoon of sugar into each bottle.
- Pour warm tap water into one bottle and cold water into the other, about a quarter full. Swirl gently.
- Stretch a balloon over the top of each bottle.
- Look every ten minutes. What happens to the balloons?
- Draw the two balloons. Which one grew more?
Play: Helpful or harmful?
Read each card. Is the microbe helping us, or can it make us ill? Pick the right box.
Your best score is kept only on this device. Nothing is sent anywhere.
Quiz
Other ages: Ages 10–11 · Ages 15–16