From Cradle to Grave: Product Lifecycles

3月 20 2011

Source: TeachEngineering Digital Library

Summary Information

Keywords:

life cycles, product, assessment, inventory, environmental impact, manufacture, materials, reengineering

Topic:

Earth Science

Biology

Computer Science

Estimated Time Required:

less than 1 hour

Target Grade (Ages):

Grade 7 (Ages 12-13)

Diversity Indicators:

This activity engages different types of learners. It may be difficult for students with limited fine motor skills to manipulate a screwdriver, etc. to disassemble products so be sure to group students with limited motor skills with students who can use a screwdriver.

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LESSON

Instructional Resources

Background:

As an introduction to engineering, you may choose to watch the What is Engineering? video below.

What is Engineering

Engineers consider the environmental impacts to our air, water and natural resources when creating a new product. To do this, engineers consider the entire life cycle of a product — from materials acquisition, materials processing, manufacturing, packaging, transportation, use and disposal of the product. These represent all the life phases of a product, similar to the life cycle of an animal found in nature.

For example, butterflies pass through four stages during their life cycle: egg, caterpillar, chrysalis and butterfly. You can use the example of a butterly and ask students the following questions to help them compare and contrast product life cycles with the life cycles of living things.

What are some steps of the life cycle of a butterfly? (Answer: birth, caterpillar, chrysalis, butterfly, decompose.)
What are some steps in the life cycle of a product? (Answer: materials acquisition, materials processing, manufacturing, packaging, transportation, use and disposal.)
How is the life cycle of an organism similar to the life cycle of an engineered product? (Possible answers: Both life cycles follow the object from birth to death, or beginning to end. Both cycles involve the flow of energy through the lifetime of the object.)
How do the two cycles differ? (Answer: Often the life cycle of a product ends with disposal, where the life cycle of a natural organism is recycled into nutrients in the Earth. Looking at the life cycle of a product helps us understand the Earth's natural resources and energy and, particularly, how we produce waste.

An engineer uses a life cycle assessment to measure how much energy and impact a product has on the environment, from its creation to its final disposal. There are several general steps to determining the overall environmental impact of a manufactured product. The first step is called aninventory analysis. In this step, the product's energy and materials that are used during the life cycle are calculated. A number value is assigned for energy and physical materials for all the phases of the life cycle (materials acquisition, materials processing, manufacturing, packaging, transportation, use, and disposal of the product). The next step is an impact analysis, where the number values from step one are added together. This final number represents the total impact on the environment. The lower the number, the less negative impact the product has on the environment. Lastly, an improvement analysis is performed to determine if there is any way to reduce the product's impact on the environment. For example, conserving energy or water during any of the phases of the life cycle or exchanging materials for less hazardous waste producing ones would help reduce the impact. Engineers sometimes design products with durable parts that will have a long lifespan, and other times they design products that are designed to last a relatively short amount of time, but have easy to reuse or recycle parts. Then, the changes are inserted back into the inventory analysis to determine if the total environmental impact can be reduced.

There are several types of life cycle assessments for engineered products. Some of them include:

Cradle-to-Grave: The full life cycle of a product from raw materials (cradle) to the disposal phase (grave).
Cradle-to-Gate: A partial product life cycle assessment that investigates a product from raw materials (cradle) to the gate of the manufacturing facility before transportation to the consumer.
Cradle-to-Cradle: A product life cycle assessment, where the end phase includes recycling of the product into a new product. The recycled product can be identical or different to the original product.

A great example of a product manufactured for cradle-to-cradle is a Nike sneaker. This is a product students will be familiar with, and designers at Nike have been working to create a product that will not add harmful waste to the environment and can be engineered with sustainable inputs. For more information visit: http://www.mcdonough.com/writings/inspiration_innovation.htm

Materials:

Pencils
Any manufactured product to analyze (i.e. VCRs, clock radios, etc.) with original packaging, if possible
Screwdrivers, scissors, etc. for disassembling product
Cub Life Cycles Lesson Activity Worksheet

Procedure:

This activity gives students an idea of how a life cycle assessment can be useful. The numbers on the worksheet are fictional and are only used to compare the environmental impacts of different objects to each other. In a real engineering life cycle analysis, the numbers of each step are determined using actual measurable inputs and outputs of energy, electricity, raw materials, water, waste and emissions.

Informational Videos

The following videos may help inform your teaching of this lesson:

Differentiated Instruction Video

Asking Good Questions Video

Before the Activity

Gather several metal and plastic products for the students to reengineer. Some example items might include a broken CD player (or old VCR player if you can find one!), a coffee pot, a stapler or a children's toy.
Provide a selection of screwdrivers, etc. to have the students take apart the products.

With the Students

As an introduction, have students listen to Life Cycle of a Cell Phone (audio)

Life Cycle of a Cell Phone
Divide the class into teams of two.
Give each student pair a product with which to complete a sample life cycle assessment.
Have students follow along with the Cub Life Cycles Lesson Activity Worksheet in determining a hypothetical number value for the impact of their product on the environment. (Remind students that the number is fictional, and for comparison purposes only.)

Cub Life Cycles Lesson Activity Worksheet
Give students time to complete the life cycle analysis of their product. (Note: more complex products will take longer to analyze than simple products, such as a hair brush. They are more interesting too! Choose your products wisely, noting that if one group has a hairbrush while another has a toaster, the groups may finish at different speeds.) During this time, students can take apart the product to get a better idea of the components and manufacturing process.
Ask students to share the total impact analysis score with the rest of the class. Create a class list of products and their scores on the board. Discuss the range of impacts the products have on the environment.
Have students think about modifications they could make to the life cycle of their product. Have them complete their improvement analysis on their worksheet and discuss any improvements with the class. Are there any recurring ideas for improvement in the class?

Safety Notes

Be sure to read any safety warnings that came with the products to be sure that disassembling them will not put students at risk of injury or in contact with harmful substances.

Make sure students are careful when taking apart their products. If you don’t want students to take apart the product, you can disassemble the product first, and then show students.

Extensions

Have students look up the life cycles of some common products. A cell phone is a good example of a product that has changed significantly over time, from amount of materials, to packaging and accessories. Cell phone parts include the case, display, wiring, keypad, microphone, speaker, antennae, and battery. Have students create a life cycle assessment for the various parts of a cell phone. The life of a cell phone averages about 18 months in the United States. Have students compare the life cycle assessment of a cell phone to conventional landline phones.

You may also want to share this podcast on the Lifecycle of a Cell Phone with your students to inform their work:

Life Cycle of a Cell Phone

Have students research more about the development, use and disposal of plastic in products from toy dolls to cars. In fact, plastics account for 25% of all waste in landfills when buried. There are several online web sites that report the amount of plastics in different products and discuss the options for recycling plastics. Have students create a brochure for their school community about the use of plastics and where to dispose of them properly.

Have students research electronic waste and again come up with a brochure or information campaign to inform their community about proper disposal. Some electronics contain hazardous materials and should not be thrown out with regular trash.

Older Students: Have older students look up the raw materials (oil, natural gas) that go into making plastics and different metals (ore). Have the students create a scoring system to distinguish different ores and raw materials by their difficulty of extraction from the Earth and limited availability.

Younger Students: Use easier products, such as a mechanical pencil or a tape dispenser. Less complicated products will help younger students understand the concepts behind the life cycle assessment.

Other suggestions to extend this activity can be found at TeachEngineering, including the original Product Development and the Environment activity and the Life Cycles activity.

Assessments and Rubrics

If you are interested in learning how to make your own rubric for this or other lessons, you may be interested in watching the How to Make a Rubric video below.

How to Make a Rubric

Or, you can choose to use or customize the one created for this lesson plan below.

Product Lifecycle Rubric (XLS)

Product Lifecycle Rubric (PDF)

Informational Video

The following video may help inform student assessment:

Asking Good Questions Video

Pre-Activity Assessment

Class Discussion: Solicit, integrate and summarize student responses.

Have the students think about the different parts and pieces that make up a product by holding up a common item, such as a stapler. Create a class list of all the parts of the stapler on the board.

Prediction: Have students predict the outcome of the activity before the activity is performed.

Show students several examples of products that they will be analyzing during this activity. Ask them to predict which products will prove to have the largest impact on the environment throughout their life cycle.

Activity Embedded Assessment

Worksheet: Have the students follow along with the activity on the worksheets. After students have finished their worksheet, have them compare answers with their peers.

Post-Activity Assessment

Considering Design Trade-Offs: Have students think about their suggested product improvements from the worksheet. Tell them that engineers must sometimes consider trade-offs in their designs. For example, will reducing the impact on the environment by reducing the amount of materials in the product actually reduce the durability and effectiveness of the product? Have the students decide if there are any similar or possible product trade-offs that should be considered in their suggested product improvements.

Diagramming: Have the students draw the life cycle of their product. On their drawing, have them detail the materials, processes, and energy involved in each phase of the life cycle. The phases they should include are: materials acquisition, materials processing, manufacturing, packaging, transportation, use and disposal of the product.

External Resources

Environment Protection Authority Victoria: Additional life cycle activities for students

PBSKids.org: Videos to get kids thinking about where things come from and what happens when things get thrown away

TeachEngineering Digital Library: Original Product Development and the Environment activity

United States Environmental Protection Agency: Life cycle assessment framework

United States Environmental Protection Agency: Life cycle of a cell phone

Credits

This material was adapted from the Life Cycles lesson, created through the Integrated Teaching and Learning Program at the College of Engineering and Applied Science at the University of Colorado at Boulder. The TeachEngineering Digital Library is a free, online collection of teacher-tested K-12 engineering activities, lessons and units aligned to educational STEM standards, funded primarily through the National Science Foundation.

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