Lesson - Biomass Energy Blow It Up Lab


Title: Biomass Energy – Blow It Up Lab
Grade: 6th Grade
Duration: 45 Minutes

In this lab, you will watch as banana and other fruits/vegetables, decompose over a period of time. Do you think that the decomposing material can inflate a balloon? Complete the following lab to find out!


  • 4 – extremely ripe bananas
  • 1 – any other fruit or vegetable (ex: apples, oranges, grapes, melons, lettuce, cabbage)
  • 3 – paper bowls or plates
  • 1 – plastic fork and knife
  • 3 – 20 ounce plastic bottles
  • 3 – balloons
  • Measuring tape
  • Funnel (optional)
  • Food Processor or blender (optional)


During this experiment you will be closely making observations about what occurs. Make sure to follow the procedures and document what happens for the next few days.

1. Make sure that you have 3 (three) empty 20 ounce bottles.

2. First, you will be peeling one of the ripe bananas.

3. Place the banana on a bowl or plate.

4. Next, mash the banana with a fork. Make sure that there are no lumps. (You may use a food processor or blender).

5. Carefully scoop up the mashed banana and place it into Bottle #1. (WARNING: This will be messy. It may be easier to scoop it up and place it in the bottle with the plastic knife and/or you can use a funnel.

6. After all of the mixture is in the bottle, carefully place the balloon over the mouth of the bottle. Make sure that you do not make any holes in the balloon as your stretch it.

7. For Bottle #2, repeat steps 2–6 above one fruit or vegetable of your choice. This will be done in order to compare if using a different fruit/vegetable will have a different result.

8. For Bottle #3, repeat steps 2–6 using 3 (three) bananas. This will be done in order to compare if the amount of material will change the result.

9. Place all three bottles in a warm, sunny spot.

10. Clean-up. If proper clean-up is not completed, you may begin to notice an unpleasant scent.

11. Watch the bottles for about a week or so.

12. Record your observations daily.

  • What is happening to the banana/fruit/vegetable?
  • What is happening to the balloon?
  • Is the balloon inflating? If so, what is causing it to inflate?
  • How long did it take for the balloon to begin inflating?
  • What is the difference in growth rate between Bottle 1, 2, and 3?
  • Which fruit/vegetable decays the fastest? How do you know?

13. Measure and record the circumference of the balloon each day to determine the effect the decay is having on the balloon.

14. Discuss the results.