Breathing Bugs
Soil is full of tiny, microscopic living things called microbes that keep our planet healthy. In this activity, we'll see how soil "breathes" by watching a balloon fill up as these tiny helpers release gas.
Fun Facts/Information:
- SoiI microbes munch on old plants and other leftovers from nature, turning them into food for new plants. When they eat, they also breathe out a gas called carbon dioxide (Co2).
- A handful of soil contains more microbes than there are people on earth!
- Some microbes are used to create foods Iike yogurt, pickles, cheese, and bread.
- Microbes have been on Earth for billions of years - long before dinosaurs.
- Here at ALCOSAN, we also use microbes (that we call "bugs") to help us clean dirty water!
Learning Objectives:
- Students will recognize that soil contains microscopic life that keeps our planet healthy.
- Students will observe evidence of microbe respiration by watching a baIloon fill with gas.
Materials:
- 1 Clear plastic or glass bottle (about 16 oz.)
- 1 Small balloon (about 6 inches)
- SoiI (from your yard, garden, or park)
- Sugar
- Water
- Measuring spoon and cup
- 2 oz. gravel
Safety Considerations:
- Make sure to wash your hands after touching the soil. Some microbes can make you sick!
- Do not eat or taste any of the materials (soil, sugar water, flour, etc.)
- Dispose of soil and water properly after the experiment. The soil should go outside or into the trash, not down the sink! Recycle the bottles if possible.
Procedure:
- Fill the bottle about 3/4 full with soil.
- Mix 1 tablespoon of sugar in about 1/2 cup of water until dissolved. In this experiment, the sugar will work as "food" for the microbes!
- Slowly pour the sugar water into the soil until it feels moist, but not muddy.
- Stretch a small balloon over the mouth of the bottle. Make sure air is not entering or escaping the bottle.
- Place the bottle in a warm spot (from 68°F to 86°F).
- Record your observations every 2 days for the first two weeks, then weekly after.
Discussion Questions:
- Did the balloon grow? What does that tell us about the microbes in the soil?
- How do microbes help keep our soil, plants, and water healthy?
- Based on this experiment, what are two things that microbes need to survive? How is that similar to humans?
- Remember: why does ALCOSAN use microbes?
Extensions:
Now that you've seen what happens with sugar water, try changing one thing at a time to see how it affects the balloon:
- Different Foods: Try adding vegetable scraps or leaves. Do microbes like some foods better than others?
- Different Soils: Use soil from a garden, playground, or forest. Which soil "breathes" the most?
- Water Only: What happens if you just add water instead of sugar water?
- Temperature: Place one bottle in a warm spot, and another in a cool spot. Does temperature change how fast the balloon grows?
- Amount of Sugar: Double the sugar in one bottle. Does more food make a bigger balloon? Did the balloon grow? What does that tell us about the microbes in the soil?
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