As an introduction to engineering, you may choose to watch the What is Engineering? video below.
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
Comments
This is a really cool lesson!
Great Lesson
It'd be awesome to post some actual footage of this lesson being done. Any takers? I'd like to see pros/cons and good/bad and what you reflected on as you finished the lesson.
This is a unique, rich,
This is a unique, rich, constructive lesson. I really like the intent of the lesson comparing the life cycle of animals and product. I modified the lesson but kept the integrity of the lesson. As an activator I use a short clip from "How Things are Made" and another clip from Journey North on the life cycle of a butterfly. My second grade students and I discussed and recorded what we know about butterflies. I asked the students if they agreed with a posted statement if goods (products) also have life cycles? Most of the students stated no, which was what I expected. I did not address or implement the worksheet but as I stated before the integrity of the lesson stayed in the forefront of my objectives. Moreover, I added several book resources that provided discussion points, background knowledge, and comparison sources of life cycles. The books may be too elementary for seventh graders, but sometimes simple is better. Anyway, I used several books from a series called Start to Finish by Shannon Zemlicka, "From Rock to Road," "From Wheat to Bread," "From Sea to Salt," "From Milk to Ice Cream," From Tree to Paper," "From Sheep to Sweater," and four books from a series titled "Materials, Materials, Materials Wool" and "Materials, Materials, Materials Glass" by Chris Oxlade. I intend to implement the lesson again with modifications. I want to spend more time on the construction of products. However, at the end of the session, which in the future I plan to expand to several days, my second graders wrote the close "I used to think but now I know" and stated that yes, products have life cycles. In fact, since the lesson, which was over one month ago, my students are stating that this product has a cycle!
This is a fun lesson. I
This is a fun lesson. I really like the way it connects the products life cycle to living things life cycle. You could open it up to have each group come up with (or research) the life cycle of an animal or plant from a different ecosystem or biome to increase variety in their answers.
Great lesson. Gives students
Great lesson. Gives students a good insight into how a product is produced and whether the product has large or small impact on the environment. Remember to make the students separate the physical products and examine them.
Felicito el trabajo realizado
I enjoyed your lesson! In my
good
Good lesson plan
Me parece muy interesante y
Esta unidad está bastante