Teaching sequence

Work through this resource material in the following sequence:

10 minutes

Part A: Understanding the problem - Our plastic addiction

30 minutes

Part B: Exploring the challenge - 30 Million toothbrushes

20 minutes

Part C: Sharing the solution

Learning intentions:

Students will:

understand the positive impacts of reducing plastic waste through mathematical investigation.

Success criteria:

Students can:

identify and use statistics
identify the impact we have on our planet
calculate the impact of cutting back on the amount of toothbrushes we waste each year.

Part A: Understanding the problem - Our plastic addiction

Step 1

Explain to students that in this lesson, they will be using maths to understand the wasteful ways we use plastic, and to calculate how we can fix part of the problem.

To begin, ask students to spend a moment thinking about all the plastic they have used or come into contact with today. Invite all students to stand up. Explain that as the following statements are read out, they are to sit down if the answer is yes. If students sit down, they are to stand up again before you read the next question.

Invite all students to stand and begin reading out the following statements:

I've used a mobile phone today
I drank water from a bottle today
I traveled to school in a car or bus
My uniform is made out of polyester
I drank from a straw today
I used shower gel today
I brushed my teeth this morning

Facilitate a class discussion using these guiding questions:

What did each statement have in common?
- Suggested answer: If students sat down they used plastic today.
Did you expect to have used so much plastic today?
- Suggested answer: The use of some plastic may not be as obvious as others. For example: micro-beads are found in some shower gels and polyester is a type of plastic used to make clothing.
Were you surprised that some of these products had plastic in them?

Step 2

Watch the following clip as a class (also found on the Student Worksheet). As students watch, invite them to record their answers to the following questions on the Student Worksheet:

What are some of the numbers mentioned in the clip?
What do the numbers mean?

Plastic addiction - (https://vimeo.com/1056608395/7354e5b897)

Step 3

After watching the clip, discuss with students the numbers mentioned in the video and record their responses on the board. If not mentioned by students, highlight the statistic that “Every year in Australia, we use around 30 million plastic toothbrushes, which just get thrown away”.

Ask students

Do they know what happens to the toothbrushes once they are thrown away?
- Suggested answer: they end up in landfill or end up in our oceans.
Can they explain why plastic pollution is an issue?
- Suggested answer: Plastic never truly breaks down. Other waste materials – like paper or glass – break down eventually. However, plastic breaks into smaller and smaller pieces and ends up polluting our environment. Over 6 million tonnes of rubbish makes its way into the world's oceans each year, and scientists have concluded that 60-80% of marine debris is initially discarded on land. The main component of this litter is usually plastic, such as toothbrushes.

Part B: Exploring the challenge - 30 million toothbrushes

Step 1

It’s now time to present a challenge to students. Explain to students that they are going to tackle the problem of reducing the amount of plastic toothbrushes that end up as pollution. Students will be using maths to address this real-world problem and will support their claims with data. Students are to think about which statistics would convince people about the importance of reducing plastic waste.

Read the following challenge to students:

'How might we cut back on the number of plastic toothbrushes that go to waste in Australia, so that we only throw away half the amount that we do now? What would the impact be?'

Step 2

Explain that to be able to find a solution to the challenge, students need to know some important facts. They will find some of these facts useful in developing a solution, while others will not be of use. It will be up to them to think carefully about each fact and decide what matters.

Hand out the Plastic Statistics Factsheet. As a class, go through the individual statistics on the factsheet - check if students are unsure about the meaning of any facts. You can ask students clarifying questions, such as:

Which statistic tells us about the weight of biodegradable toothbrushes?
What are biodegradable toothbrushes?
Why might a biodegradable toothbrush be likely to cost $6.00?
How many times per year might a person buy a toothbrush if they are taking good care of their teeth and gums?

Step 3

To solve the challenge, students are to select an 'impact area' to tackle (on the Student Worksheet) and use statistics to mathematically calculate a way to reduce the number of toothbrushes being thrown away each year. They should do this by answering the questions on the Student Worksheet. Explain that as a class, they will share the findings to their investigation questions, then vote on which ideas would be the most convincing to people in Australia.

Before students get started, go through the Student Worksheet together. As a class, choose one of the 'impact areas' to go through so that students have a clear understanding of what to do. For example, for the impact area, ‘Amount of money spent’, explain to students that:

A useful statistic for this impact area is: 'A plastic toothbrush costs around $2.00 to $4.00'. A statistic that is not useful is: 'Biodegradable toothbrushes can weigh between 10 to 25 grams'.
If you wanted to know how much was going to be spent on plastic toothbrushes over the next 45 years, for example, you could calculate 30,000,000 x $3.00 x 45. (How would you work this out by hand?)

You may decide whether this impact area will remain an option for students to investigate themselves.

Step 4

Students should continue to work through the Student Worksheet and answer questions about their impact area. As students work, support their learning by providing prompts and asking questions, such as:

How would you work out the number/cost/weight of toothbrushes over 2 years? 10 years? more?

You may allow calculators if students need them, or students could work in pairs or groups of three.

Need an extension?
What calculations could you do with other statistics (e.g. the biodegradable toothbrushes) that could help in convincing people about the importance of reducing plastic waste? Include these in your findings.

Part C: Sharing the solution

Step 1

Get students to share what they have come up with. You can run this in different ways; for example, students can share what they’ve done in smaller groups first. Each group then nominates one person to share with the whole class. Or, each student could have 30 seconds to present what they’ve done to the entire class.

To make this run efficient, each student could stand up and present from their desk. Ask students to decide whose solution they believe would be most effective for convincing people to reduce their plastic waste; it is important to also consider whether the mathematics that has been presented is accurate.

Allow students 5-10 minutes to ask questions of each other to clarify the details of solutions presented by their peers.

Students should vote for their preferred solution by writing it down on a sticky-note.

Step 2

After the votes have been counted is a useful opportunity to go over what the student with the most votes did well, but also what was successful about other students’ solutions. Highlight instances where students have critically reflected on the data that they had access to.

Finally, ask students to reflect on what they have learned about using statistics to solve the toothbrush problem. For example:

Which statistics were most useful/least useful in solving the problem? Why?
Does it matter if you didn’t use all of the information that was available to you to solve the problem? Why/Why not?
What are some things you thought about that helped you to decide if a statistic was useful?

Assessment

What can the students do, say, make or write?

Students can identify and use relevant statistics to calculate the impact of reducing waste. Students can perform appropriate calculations with these statistics. Students can justify their ideas.

Take it further

Invite students to apply their learning in a real-world context by participating in the Ocean Guardians Creating Change - Social Action - Year 7 & 8.

Blue - Do the Maths on Plastic Toothbrushes

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Summary

Learning intentions:

Students will:

Success criteria:

Students can:

Lesson guides and printables

Lesson Details

Skills

Curriculum Mapping

Resources Required

UN Sustainable Development Goals

Additional Info

Related Professional Learning

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