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C1.1 · Assess the life-cycle impacts of materials in consumer products

Learn to assess the life-cycle impacts of materials in consumer products through clear examples and targeted practice.

Ontario Grade 9 Science

Chemistry: The Nature of Matter

Assessing impacts from making a product to what happens after use

A reusable water bottle may be made of metal, plastic, or glass. A disposable bottle may use less material per item, but it is usually used for less time. Which choice has the smaller impact? The answer depends on more than the material name. We need to consider how the product is made, moved, used, and handled when it is no longer needed. This is a life-cycle assessment: a comparison of impacts across the stages of a product’s life. It is a way to organize evidence, not a guarantee that one product is best in every situation.

What you will learn

Identify the main stages in a consumer product’s life cycle.
Describe ways materials can affect people and the environment at different stages.
Compare products fairly by asking whether they do the same job for a similar length of time.
Use evidence carefully and explain the limits of a comparison.

1. Follow a product through its life cycle

A consumer product is an item people buy or use, such as a backpack, phone, or food container. Its material is the matter it is made from. Before a material becomes part of a product, it may be collected from nature or recovered from used items. These steps are called obtaining raw materials. Raw materials are the starting materials used to make something.

The life cycle continues through manufacturing, transport, use, and end of life. Manufacturing means turning materials into a product. Transport means moving materials and products between places. The use stage includes the product’s useful life and any resources it needs while being used. End of life means what happens when the owner no longer uses it: it may be reused, recycled, burned, buried, or discarded in another way.

Each stage can have impacts. An impact is a change that affects people or the environment. Collecting materials can disturb land or habitats, which are places where living things live. Manufacturing can use energy and water and can create waste or pollution. Transport uses energy. During use, some products need electricity, water, or replacement parts. At end of life, a product may become waste, or some of its materials may be recovered for another use.

Life-cycle stages are connected; an impact can occur before a product reaches the buyer.
Consider energy, water, waste, pollution, and effects on land and living things.
Recycling can recover materials, but it does not erase impacts from earlier stages.

2. Compare products fairly

Start with a clear question. For example: Which bottle has lower impacts while providing drinking water for one student over a school year? A fair comparison asks products to do the same job. It also considers how long they last and how often they must be replaced. Comparing one durable bottle with one disposable bottle, without considering how many disposable bottles provide the same service, can give a misleading answer.

Use the same boundaries for both choices. A boundary is the set of stages included in a comparison. If transport is counted for one product, it should also be considered for the other. Decide which impacts matter to the question. A comparison might look at material use, energy, water, waste, and possible harm to habitats. These are different kinds of evidence and should not be treated as one simple score unless the method for combining them is clearly explained.

A simplified life-cycle model can help organize questions. It does not show every detail of a real supply chain. A product may be made in several places, and its impacts can depend on local energy sources, transport distance, how carefully it is used, and whether local recycling is available. A model is useful for asking what to investigate, but it is not itself proof of an impact.

Compare products that provide the same service for a similar length of time.
Use the same life-cycle boundaries and impact measures for each option.
A model organizes the comparison; evidence is needed to support conclusions.

3. Use evidence, then make a careful assessment

Evidence is information that can support a conclusion. Useful evidence might include product information about material content, information about how a material is made, or local guidance about waste and recycling. Check who produced the information, what stages it covers, and whether it applies to the products being compared. If figures are estimates or come from different settings, say so.

A safe inquiry can begin without experiments. Choose two products that do the same job. Read their labels and reliable product or local waste information. Make a list of questions for each life-cycle stage: What materials are used? What resources may be needed to make and use the product? How long can it serve its purpose? What options exist at end of life? Record which answers are supported by evidence and which remain unknown. Do not guess missing facts or treat a marketing claim as independent proof.

Assessment includes a judgment about the evidence. A scientific statement might be that a product contains a stated material, if its label supports that claim. A social or ethical judgment might be that avoiding a particular waste stream is important. That judgment can guide a choice, but it is not the same kind of claim as a measured or documented impact. A strong conclusion names the evidence, notes important unknowns, and explains why the evidence matters to the decision.

There may be trade-offs. A product could use more material to make but last longer. Another could be easier to recycle where a person lives. Avoid declaring a material always better. State which option seems preferable for the stated purpose and evidence, and what could change that conclusion.

Check the source, scope, and limits of evidence.
Separate evidence-based claims from personal, social, or ethical priorities.
A careful assessment can recognize trade-offs and uncertainty.

Questions to ask at each life-cycle stage

Stage	Possible question
Obtaining materials	What materials are needed, and what may happen to the places they come from?
Manufacturing	What resources, energy, or waste may be involved in making the product?
Transport	How is the product moved, and what information is available about that movement?
Use	How long does it last, and does it need other resources while being used?
End of life	Can it be reused or recycled locally, or does it become waste?

Worked example

Map the life cycle of a lunch container

A student wants to understand possible impacts of a reusable lunch container. Organize questions about its life cycle without assuming facts that are not known.

Questions across a product life cycle

A simplified sequence for organizing investigation questions. It does not show every supplier, route, impact, or possible end-of-life pathway.

Name the stages
Begin with the material source and follow the product through making, transport, use, and end of life. The sequence helps prevent attention from stopping at the store shelf.
Ask evidence questions
For each stage, ask what resources or waste may be involved and what source could answer the question. For example, the product label may identify material, while local waste guidance may describe whether that material is accepted for recycling. These sources answer different questions.
State what remains unknown
If the source does not say how much energy was used to make the container, record that as unknown. Do not turn a missing value into a zero or invent a measurement.

Answer: The student has a useful plan for gathering and sorting evidence, but not yet enough evidence to rank the container’s impacts.

Check: A life-cycle map identifies questions and stages. It does not provide measurements or prove that one product has lower impacts.

Worked example

Compare hypothetical container information

A class uses a hypothetical practice summary for two containers. Container A lasts for one school year and is accepted by the local recycling program. Container B lasts for one term and is not accepted there. The summary gives no information about manufacturing energy, material amounts, or transport. What can the class conclude?

Evidence and unknowns

Hypothetical practice information only. The diagram separates stated information from a broader conclusion that the evidence cannot yet support.

Check the comparison
The containers are being compared for a school-year use. Since B lasts only one term, more than one may be needed to provide that service. This makes a simple one-container-to-one-container comparison unfair.
Use only the stated evidence
The summary supports a limited claim: A lasts longer according to the hypothetical information, and the local program accepts A but not B. It does not establish the products’ total impacts.
Name the limit
The missing information about materials, manufacturing, and transport could affect the comparison. The class should not claim that A has lower total life-cycle impacts based only on the provided details.

Answer: A appears more suitable for the stated local recycling option and lasts longer in the hypothetical summary. The evidence is insufficient to decide which has lower total life-cycle impacts.

Check: The conclusion matches the evidence without filling gaps with guesses.

Worked example

Make a balanced recommendation

A student compares two hypothetical bags for carrying the same books. Bag X is reported to last longer but uses more material to make. Bag Y uses less material to make but may need replacement sooner. The report gives no measured totals. How should the student assess them?

A trade-off in a product comparison

Hypothetical comparison. The branches show reported advantages, not measured total impacts; the figure is a simplified reasoning model.

Keep the purpose the same
Both bags carry the same books, so the comparison has a shared purpose. The student should also consider the full time each bag can provide that service.
Recognize the trade-off
The report describes one possible advantage for each bag. Longer use may reduce the need for replacement, while using less material may reduce material demand at the start. Neither point alone proves which bag has lower overall impacts.
Give a qualified conclusion
The student can say that X may be a better choice if it lasts substantially longer, while Y may have an advantage in initial material use. The report lacks totals and other life-cycle details, so the final comparison remains uncertain.

Answer: The evidence shows a trade-off, not a clear overall winner. A stronger assessment would need comparable information across the relevant life-cycle stages and a clear statement of how long each bag is expected to serve.

Check: The recommendation distinguishes reported information from a broader conclusion and identifies what more evidence is needed.

Common mistakes and how to avoid them

Choosing a product because its material sounds environmentally friendly.

Correction: Consider the whole product life cycle and evidence for the specific products being compared.

Comparing one long-lasting item with one short-lived item as if they provide the same service.

Correction: Consider how many replacements may be needed to provide the same service over the same period.

Assuming that recyclable means recycled.

Correction: Check whether the product is accepted by the local program and remember that recycling does not remove earlier impacts.

Treating an unknown impact as zero.

Correction: Label missing information as unknown and explain how it limits the conclusion.

Lesson summary

A product life cycle includes obtaining materials, manufacturing, transport, use, and end of life.
Impacts can include resource use, waste, pollution, and effects on land and living things.
Fair comparisons use the same purpose, similar service period, and consistent boundaries.
A strong assessment uses evidence, notes uncertainty, and explains trade-offs without claiming more than the evidence supports.

Check your understanding

Question 1

Two containers are compared for carrying lunch for a full school year. One lasts only a month, while the other lasts the year. What is the fairest next step?

Compare just one of each container because both carry lunch.
Consider how many short-lived containers may be needed to provide the same service over the year.
Choose the container with the more familiar material.
Assume the longer-lasting container has no impacts.

Show answer and explanation

Consider how many short-lived containers may be needed to provide the same service over the year.

A fair comparison considers products that provide the same service for a similar period. The longer-lasting product may reduce replacements, but other life-cycle evidence is still needed.

Question 2

A product label says a container is recyclable. What does this information alone prove?

The container will be recycled everywhere.
Making the container caused no pollution.
The label makes a claim about recycling, but local acceptance and actual handling still need to be checked.
The container has lower total impacts than every alternative.

Show answer and explanation

The label makes a claim about recycling, but local acceptance and actual handling still need to be checked.

Recyclability does not show that every local program accepts the item or that it will actually be recycled. Nor does it describe impacts at other life-cycle stages.

Question 3

A comparison has information about material use but none about transport or product lifetime. What is the best conclusion?

The product using less material must have lower total impacts.
The comparison is incomplete, so its conclusion should be limited to the material information provided.
The missing information can be treated as having no impact.
The products cannot be compared in any way.

Show answer and explanation

The comparison is incomplete, so its conclusion should be limited to the material information provided.

The available evidence can support a limited statement about material use. Missing stages and lifetime information prevent a confident conclusion about total life-cycle impacts.

Key terms

Consumer product: An item people buy or use.
Material: The matter used to make a product.
Life cycle: The stages a product passes through, from obtaining materials to what happens after use.
Impact: A change that affects people or the environment.
Evidence: Information that can support a claim or conclusion.
Boundary: The set of life-cycle stages included in a comparison.
Trade-off: A situation in which an option has an advantage in one area and a disadvantage in another.

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About this lesson and its review

Published by DoAssignment. This reviewed lesson follows Ontario Grade 9 Science (SNC1W), expectation C1.1. It is a study resource, not an official curriculum publication.

Before publication, content is checked for structure, mathematical or chemical notation, calculations, course boundaries, and readability. Errors can still occur, so corrections are welcomed.

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