Activity - Life Cycle of a Candy Bar
Created by Melissa Bilec, Alexander Dale & Cassie Thiel
University of Pittsburgh Sustainability and Green Design Group
www.engineering.pitt.edu/SGD
Time: 20-30 min (or longer)
Appropriate for: Grades 5+
Materials required: Blank paper (bigger is better), markers, candy bars (optional)
The purpose of this activity is to discuss and visualize the various materials and supply chains that
go into making a common object - the candy bar. Students draw the basic life cycle and include
specific materials, generating diagrams that can be used for further discussion of environmental
impacts, engineering design, or consumer choices.
Key terms
• Life Cycle: All of the materials and steps required to create a product or service, often focusing on
four specific stages: raw materials extraction, processing and transportation, use, and end-of-life.
• Cradle-to-grave: A life cycle that begins with extracting materials from nature (e.g. mining) and
ends with disposal into a landfill, with minimal resource recovery, recycling, or reuse.
• Cradle-to-cradle: A life cycle that connects the end-of-life of one or more products and the raw
materials for another. Maximizes resource recovery, recycling, and reuse.
• Life Cycle Analysis: A method for calculating quantitative total impacts over a product or service’s
life-cycle. A common example is a carbon footprint, which is an LCA calculated only using
greenhouse gas emissions.
Figure 1: Layout and guide to activity
Raw Materials
Processing
Step 4 Production
Components
Step 2 Food
Step 3 Wrapper
End-of-Life
Step 5 Disposal
Candy
Bar
Procedure
The end result of the activity will be a diagram with five stages from left to right: raw materials,
processing, basic components, a candy bar, and disposal. These are created by working backwards
from the candy bar to raw materials, and then forwards to disposal. See Figure 1 for a guide
1. Work in small groups or as a whole class. Draw a candy bar (or write the words) on a piece of
paper, centered on the short axis, 75% of the way along the long axis.
2. Ask students what materials go into a candy bar (ex. chocolate, pretzels, caramel). We often use
Take 5s or Snickers because they have easy components. Add each component in a bubble
towards the center of the paper.
3. When students run out of edible items, ask if there are other materials. Point out (if no one has
mentioned it) that you also need a wrapper and/or bag. Add these materials to the components
stage.
4. For each component, talk about what goes into producing it - growing things? processing things?
moving things around? - and add additional connected items to the chart. You should have some
items in both raw materials and processing now, connecting to components and then to the
candy bar.
5. Finally, talk about wastes. The wrapper is probably thrown away - they’re an amalgam of metal,
plastic, and glue that can’t be recycled. The food gets turned into human energy and waste.
Having these items on the chart is important, but the form is up to you.
Other Resources
Autodesk’s Sustainability Workshop (sustainabilityworkshop.autodesk.com) has lots of good
videos on these concepts, with great whiteboard-style animations. There are also design tutorials on
various design-for-environment topics for more advanced classes.
For life-cycle assessment tutorials, Sustainable Minds (sustainableminds.com) is a good web-based
tool with tutorials, a simpler interface, and free trials.
LIFE CYCLE ASSESSMENT
LIFE CYCLE ASSESSMENT BASICS
What Goes In?
Chocolate
Peanuts
Peanut Butter
Pretzel
Caramel
Wrapper, Plastic
Paper Packaging
What Comes Out?
Garbage
Human Waste
Energy
http://www.candyfavorites.com/blog/tag/hersheys-take-five-candy-bar/
http://commons.wikimedia.org/wiki/File:Candy-Take5-Broken.jpg
Cocoa beans
• Growing
• Equipment
• Energy
• Transportation
Cocoa butter
• Roasting/Grinding
• Equipment Required
• Electricity
• Transportation…
Cows
• Food
• Infrastructure
• Equipment
• Transportation
Milk
• Cows
• Pasteurization
• Transportation
• Energy…
Sugarcane
• Growing
• Harvesting
• Equipment
• Transportation…
Sugar
• Sugarcane
• Processing
• Transportation
• Energy…
Chocolate
• Cocoa butter and
chocolate liquor
• Sugar
• Milk
• Equipment
• Processing
• Energy…