Activity Introduction

Quick summary: In this activity students conduct a simple experiment to determine the decomposition rates of four types of typical shopping bags: biodegradable plastic, non-biodegradable plastic, reusable shopping bag and paper. Students will test the bags over several months in three conditions: buried underground, in the sun and in water.

Learning goals:

  • Students learn that the bags that we use to carry all the things that we buy are very convenient, but their inappropriate disposal can have major impacts on the built and natural environment.
  • Students understand that choosing the right bags to carry our things is just as important as choosing the right things in the first place.

Australian Curriculum content description:

Year 7 Science

  • Identify questions and problems that can be investigated scientifically and make predictions based on scientific knowledge (ACSIS124)
  • Collaboratively and individually plan and conduct a range of investigation types, including fieldwork and experiments, ensuring safety and ethical guidelines are followed (ACSIS125)
  • Summarise data, from students’ own investigations and secondary sources, and use scientific understanding to identify relationships and draw conclusions (ACSIS130)
  • Communicate ideas, findings and solutions to problems using scientific language and representations using digital technologies as appropriate (ACSIS133)

Year 8 Science

  • Identify questions and problems that can be investigated scientifically and make predictions based on scientific knowledge (ACSIS139)
  • Collaboratively and individually plan and conduct a range of investigation types, including fieldwork and experiments, ensuring safety and ethical guidelines are followed (ACSIS140)
  • Summarise data, from students’ own investigations and secondary sources, and use scientific understanding to identify relationships and draw conclusions (ACSIS145)
  • Reflect on the method used to investigate a question or solve a problem, including evaluating the quality of the data collected, and identify improvements to the method (ACSIS146)
  • Communicate ideas, findings and solutions to problems using scientific language and representations using digital technologies as appropriate (ACSIS148)

Syllabus Outcomes: SC4-4WS, SC4-5WS, SC4-6WS, SC4-7WS, SC4-9WS. 

Topic: Solid waste

Time required: 60 mins, this experiment will take several months and can be revisited at several points during this time.

Level of teacher scaffolding: High – assist students with experiment.

Resources required: Each group will need the following items: 3 biodegradable plastic shopping bags, 3 non-biodegradable plastic shopping bags, 3 paper bags, 3 reusable plastic or cloth shopping bags, 12 short wooden or metal stakes, 4 buckets, 4 rocks, water, shovel, mallet, camera, access to student worksheet.

Digital technology opportunities: Digital sharing capabilities.

Homework and extension opportunities: This activity has opportunities for homework or extension.

Safety: Students follow class waste safety code.

Keywords: Plastic, bag, decomposition, breakdown.

* Activity adapted from: Save the Earth Science Experiments (2008), Elizabeth Snoke Harris, Lark Books, New York, USA.

 

Cool Australia’s curriculum team continually reviews and refines our resources to be in line with changes to the Australian Curriculum.

Worksheets

Teacher Worksheet

Teacher preparation:

Overarching learning goal: In this activity students conduct a simple experiment to determine the decomposition rates of four types of typical shopping bags: biodegradable plastic, non-biodegradable plastic, reusable shopping bag and paper. Students will test the bags over several months in three conditions: buried underground, in the sun and in water.

Teacher content information: The Great Pacific Garbage Patch is a vast floating mass of plastic debris that has accumulated in the Pacific Ocean. (If students are unfamiliar with the Great Pacific Garbage Patch, begin this activity by asking them to research the topic or to read the section on this topic on the Our Cool School website under 'Waste'.)

The sad truth of the Great Pacific Garbage Patch is that about 80% of the material floating around in there comes from the land, and much of it is made up of plastic bags, bottles and various other plastic items that we humans use in our everyday lives.

See what othe

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Student Worksheet

What will happen to the plastic bags? Your predictions:

1. Which type of bag do you think will break down the fastest? 

 

2. Which type of bag do you think will break down the slowest? 

 

3. Which condition do you think will cause the fastest rate of decomposition? 

 

4. Which condition do you think will cause the slowest rate of decomposition? 

 

Experiment instructions

1. To test your bags in sunlight, you will need to pin your bags to the ground in a sunny position in the school garden. Use four stakes to pin each bag to the ground (to avoid the bags being blown away). Also be sure to attach a marker to each bag so that you know which one is which. 

 

2. To test your bags in water, fill four buckets or containers with water. Put the bags into the water and use a stone or other heavy item to hold the bag under water. Attach a label to each bucket to identify the bags.

 

3. To test your bags underground, dig four holes in the schoolyard and bury your bags. Try to dig the

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