Part 2: Experiment

• Make the connection between nature recycling a tree and students recycling items such as plastic or metal. In both cases something is broken down and then used to make something new.
• Ask students for ideas about why we need to recycle plastic. Can’t nature recycle it, like it recycles a tree?
• To help answer this question, have students design an experiment to compare how a plant breaks down to how a piece of plastic breaks down. One way to do this is to put soil into two plastic bags and add fruit or vegetable matter into one bag and plastic into the other. Then observe both bags periodically until the fruit or vegetable matter is fully decomposed or for a specified period of time. To work properly, the bags must contain air when sealed. Students may come up with other ideas.
• Sealing the items in a plastic bag is just one possible way for students to observe the breakdown of the vegetable matter and the plastic. They might also place them in bins, etc. To prevent mold spores (and bad smells!) from spreading in the classroom, have students keep any open containers with vegetable matter outside.
• For younger students, work together as a class to design the experiment. Come up with a guiding question and a hypothesis. Identify elements of the experiment you will control and how you will collect your data. Write the steps on the board. You can have students set up the experiment in small groups and report their data to the class.
• Older students can design their own experiments in small groups, although you may want to come up with the guiding question as a class. Make sure that students write a hypothesis, plan out the steps they will take, and identify how they will control conditions and how they will collect the data. Because different fruit and vegetable matter will decompose at different rates, you may want to have all students use the same type or set a time limit of two or more weeks for students to collect data.
• Students should observe their experiment on a regular basis. Some ways they might collect data are to make written observations, take photos, or weigh the vegetable matter.
• If students want to observe the complete breakdown of the vegetable matter, advise them to use something that breaks down quickly, such as lettuce, an apple core, or the inside or a banana. On the other hand, if they want to weigh the material, advise them to use something that will break down over a longer period of time, such as a carrot.
• When students have completed their experiments, discuss the results. Connect back to the idea of why some things have to be recycled by people instead of by nature.
• Plan time for students to check on their experiments over at least two weeks. Avoid having students check on them every day; changes will be more noticeable if they only observe them once or twice a week. Observations and recording data should only take 5-10 minutes.
• A blank table is provided on the student data sheet. Students can adapt this table or create their own. When creating their tables, students should identify what type of information they want as column labels and as row labels. For example, students might want to include the date, their observations, and the weight:
  

  Date	I saw...	The bag weighed...

  
  

1. You observed how nature recycles a tree. Humans recycle, too. List some things we recycle.
2. One of the items we recycle is plastic. Why do humans need to recycle plastic? Work with your class. Find a way to compare how plastic breaks down to how a plant breaks down. Write the steps you will take.
3. Do your experiment. Record your data.
4. Discuss your data with the class. Did the plant decompose? Did the plastic decompose? Does this help you understand why we recycle plastic? How?

Part 3: Engineer

Students may need help getting started. For younger students, a class discussion for steps 4 and 5 might suffice. For older students, include the writing pieces.

• Review parts 1 and 2 with students. Have them look again at the Nature Recycles Trees handout and share what they remember from their own observations of the decomposing log. Ask them to recall how little the plastic decomposed in their experiment compared to the plant matter.
• Tell students that engineers and inventors are always looking for better ways to recycle items such as plastic. Challenge students to design a way to recycle plastic. Encourage them to use some of the processes they saw in the breakdown of a tree to help them with their ideas. For example, trees are broken down into smaller and smaller parts by some decomposers. Lichen use chemicals to break down the tree. How could those things apply to breaking down plastic? Have students draw their idea. Encourage them to be as specific as possible and to show how their idea would work. Older students can also create a model of their idea. These models should have some moving parts, though they will likely not be able to complete the whole process. For example, a model might focus just on how the plastic will be moved through the process or how it will be cut down, rather than showing the whole process.

1. Design a way to recycle plastic. Use what you know about how trees are recycled in nature.
2. Make a model of your idea (draw how this would work).
3. Watch the video your teacher plays. This video shows how plastic is recycled. Show students the Sesame Street Video Web Link - Sesame Street: Murray Visits a Recycling Center
4. How is your idea the same? Different?
5. We recycle plastic. Nature recycles trees. How are these the same? How are they different? Draw or write your ideas.

Reflect and Apply:

Students should be able to:

• Think about your experiment. Did anything surprise you? What errors might you have made?
• What happened in your experiment? Did this help you understand why we recycle plastic? How?
• You learned how nature recycles trees. How did this help you get ideas about how plastic might be recycled?
• Compare the two systems: how nature recycles a tree and how humans recycle plastic. What are the similarities/differences?

Extension:

Sometimes it is hard to recycle because people don’t always have the information, technology or tools they need. Read the book One Plastic Bag with students. Describe how the women of Gambia got rid of the piles of plastic bags. Ask students to find some items at home that can be reused to make something new. Have them bring their creation to class to share. Embed image of One Plastic Bag cover on page 3 of the PDF.

Journal Question: Have students reflect on how nature can inspire ideas for solving problems.

• Listen as your teacher reads “One Plastic Bag.”
• Find something at home that can be reused to make something new.
• Bring your creation to class. Tell what it is made of.
• Journal Question: How can observing nature help us to solve problems?

Additional Resources to Explore:

• Web Link - Sesame Street: Murray Visits a Recycling Center