Teaching sequence

Work through this resource material in the following sequence:

10 minutes

Tune In: What a load of rubbish

20 minutes

Find Out: Pie charts and percentages

20 minutes

Take Action: Limit the landfill

5 minutes

Reflection

Tune In: What a load of rubbish

Step 1

Ask students, What do we throw away? Write down everyone’s answers where they can be seen. Wow, that’s a lot of rubbish! Does it all go in the same bin? What different categories can we divide our rubbish into? You may have a bin system at school that you can use to set categories (for example, landfill, recycling, organic waste, soft plastics); otherwise, you can use the categories we have listed below.

organic waste
soft plastics
mixed recyclable plastics
mixed recyclable paper
mixed recyclable metals
electronics and batteries
10¢ containers
glass
other.

Use these categories to sort all of the waste that the students listed. Are there some items that don’t fit very well? Are there some items you’re not sure about?

Note: When doing this activity on a whiteboard, you can use different colours to sort the rubbish into their categories. When doing this activity on a smartboard, you can move the different items of rubbish to make the categories.

Which of these categories do you think we produce the most of at school? Record student predictions.

Find Out: Pie charts and percentages

Step 1

One way to represent the contents of our bins would be using a pie chart. Show your students ‘Pie Chart Example 1.’ and explain to students that this graph shows what was found in a classroom’s rubbish bin.

Pose the following questions to the class.

What information is this chart giving us?
What percentage does the whole graph represent?
How could we explain the value of each section?
Is there a way we can identify or estimate the percentage each section shows? What strategies could we use to work this out?

Depending on students’ prior knowledge and mathematical understanding, they may require some guidance to develop their understanding of the chart as a representation of percentages. If required, guide them towards the understanding that the chart as a whole represents 100% of the rubbish. The blue section takes up half the chart, so this will be half of 100%, which is 50%. The red section takes up one-quarter of the chart, so it will be 25%, and so on.

Step 2:

Provide students with a copy of ‘Pie Chart Example 2.’

Using the Think-Pair-Share approach, invite students to consider the following questions:

What percentage of the class rubbish was in each category?
How did you work this out?
What did you notice about how much of each type of waste there was?
What is similar or different to the previous chart? Why do you think this could be?

Note: The second graph has some significant differences from the first to prompt discussion about different approaches schools or classrooms may take to waste management. Ask students to consider why there might not be any organic waste in the second chart. Why might there be less soft plastic than in the previous class? Should there be so much paper and cardboard in the bin? It may also be relevant to note that there is no indication of the total amount each class had and that the second bin may have had less overall waste in it than the first.

Opportunity for Extension: Students with strong mathematical skills have an opportunity to find more precise percentages for the smaller sections that are more difficult to estimate. They will likely be able to immediately identify the sections that are 25% and 50% and then can use the below process to find percentages represented by the smaller sections.

Provide them with a protractor to allow them to measure the angle of each section.
They can then create a fraction out of 360 (e.g. the red section is 90°, so it could be shown as90360)
They can then simplify the fraction (14)
Then use a calculator to convert it to a decimal (1 ÷ 4 = 0.25)
Then convert the decimal to a percentage (25%)

Provision for Learning Support: For students finding it difficult to identify the percentages, provide them with the ‘Example Percentages’ resource sheet and allow them to compare the size of the sections on their charts to the examples to estimate the percentage that each section represents. Ensure they add the total of each section to ensure the chart adds to a total of 100%.

Step 3

Explain to students that the class will now explore the contents of our own bin.

Note: For safety, provide students with gloves and/or tongs to handle the rubbish. We recommend pre-collecting a bin of rubbish and checking the contents for anything dangerous (biohazardous, sharps etc.) or personal that someone may have thrown away.

Explain that the bin will be emptied, and the contents will be sorted into the following categories:

organic waste
soft plastics
mixed recyclable plastics
mixed recyclable paper
mixed recyclable metals
electronics and batteries
10¢ containers
glass
other.

Step 2

Once the contents have been sorted into these categories, discuss how they could be arranged into a pie chart format. Invite students to suggest strategies or approaches to ensure that the graph is organised accurately, with each type of material occupying the correct percentage of space.

Students might measure items by weight, volume, or number of items to determine what percentage of the bin is in that category. Once an approach has been determined, invite students to calculate the percentage for each type of waste they found.

Step 3

Using the masking tape, mark out a large circle on the tarp. You may need a hula hoop or other large circle to help you mark out the space. Have students measure the angles and put down lines of masking tape to mark out the different segments of the pie chart. On smaller pieces of tape, write down the category and the percentage and use these to label the different segments. Once your pie chart is completed, fill the segments with the rubbish, and take a top-down photograph to show the completed graph.

Extension: Would the graph change if we used a different metric for measuring the rubbish? For example, if we measured the rubbish by weight for our first pie chart, how different would it look if we measured by item count? Or by volume?

Provision for Learning Support: Students who used the ‘Example Percentages’ resource in the previous task are encouraged to refer back to it again in this task.

Step 4

Reconvene the class and invite students to discuss what they observed about the waste in the class bin, focusing on the following questions:

Was there anything about your pie chart that surprised you? Was there more of a specific type of rubbish than you thought there would be? Or less?
Should we have added any other categories?
And the big question: what should we do with this rubbish now?

Take Action: Limit the landfill

Step 1

Watch the video:

What is a landfill? (https://www.youtube.com/watch?v=aPO37Scaa5w).

At the end of the video, spark a discussion with your students using the following questions:

What did you learn from watching this video?
Do you think putting our rubbish into a landfill is the best way to manage it?

Optional Step: If you are a Western Australian School, display the article 6 Shocking Facts About West Australian Waste Generation and discuss the implications for your local communities. How does this article highlight a need for change in the state?

Step 2

Watch the video:

WA | Scheme Overview (Captions).

At the end of the video, invite students to discuss the following questions:

Why do you think the Containers for Change initiative has been developed?
What impact can this program have?
How can we maximise its impact?

Step 3. Provide students with the ‘Limit the Landfill’ worksheet and provide time for them to complete the sections answering the following questions:

What are the problems associated with landfill?
How are we contributing to this issue?
What changes can we make to help resolve this issue?

Reflection

Reconvene the class and discuss what a pledge is. Discuss why pledges are valuable and what impact they can have. Invite students to share examples of pledges they could make to contribute to the reduction of landfill.

Provide time for students to write their pledge on the second page of the student worksheet in the format:

I pledge to…

Because this will…

Select a method to store or display these pledges so that their impact continues. You may create a display in your classroom, place them all in a box and read a pledge at the end of each day or encourage students to take their pledge home to share with family or display it somewhere in the house. Selecting a method that allows the pledge to act as an ongoing reminder can enhance the impact of this personal commitment.

Differentiated Learning

Extension: When suggesting percentages for each section in Pie Chart Example 2, students with strong mathematical skills can find more precise percentages for the smaller sections with less apparent values. They will likely be able to immediately identify the sections that are 25% and 50% and then can use the below process to find percentages represented by the smaller sections.

Provide them with a protractor to allow them to measure each section.
They can then create a fraction out of 360 (e.g. the red section is 90°, so it could be shown as 90/360)
They can then simplify the fraction (1/4)
Then use a calculator to convert it to a decimal (1 ÷4=0.25)
Then convert the decimal to a percentage (25%)

They can also apply this approach when labelling percentages on the graph of classroom waste created in the next stage of the lesson.

Provision for learning support: Provide students with the ‘Example Percentages’ resource sheet and allow them to compare the size of the sections on these charts to the examples and the class chart created to determine what percentage each section would represent.

Containers for Change WA - What’s in our Bin?

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