Food Packaging Module Teachers Edition Sampler · world? The question of relevance is one your...

M O D U L E

Materials World ModulesAn Inquiry-based Science & Technology Educational Program

Teacher’s Edition

Northwestern University(847) 467-2489

FOOD PACKAGING

This project was supported, in part,by the

National Science FoundationOpinions expressed are those of the authorsand not necessarily those of the Foundation

Materials World Module Team

AuthorsBrad Goral, New Trier High SchoolKate Heroux, Lake Forest High SchoolCindy Quinn, Oak Park and River Forest High School

Module Development and Field Testing

Eric J. BaumgartnerSchool of Education and Social PolicyNorthwestern University

Misty EicheScience teacherWinterhaven Middle SchoolPortland, Oregon

Jim ErnstScience teacherSt. Juliana SchoolChicago, Illinois

Matthew HsuMaterials Science and EngineeringNorthwestern University

Barbara-Ann G. LewisCivil EngineeringNorthwestern University

Peter MartinThe Automobile Safety LaboratoryUniversity of Virginia

Prof. Brian Reiser School of Education and Social PolicyNorthwestern University

Patrice L. WashingtonMaterials Science and EngineeringNorthwestern University

MWM ProgramDirectorProf. Robert P. H. Chang

Program CoordinatorsChristine BeldenRuth Rozen

Education ConsultantRichard Goodspeed

Dissemination/Hub SitesBarbara J. Pellegrini

Network CommunicationsBin Chen

ComptrollerLinda Stewart

Product DesignSeries EditorElizabeth Kaplan

Series Graphic DesignMaria Mariottini

Module EditorKaryn Bertschi

Teacher’s Edition EditorsGlen PhelanBecky Strehlow

Module Graphic DesignPatricia Parra

Photo EditorMary E. Goljenboom

ProductionPaula Lang

Copyright ©1999 by Northwestern University. All rights reserved. No part of this work may be reproduced or transmitted in any form or by anymeans, electronic or mechanical, including photo-copying and recording, or by any information stor-age or retrieval system without the prior written per-mission of Northwestern University unless such copy-ing is expressly permitted by federal copyright law. Address inquiries to: Materials World Modules,Northwestern University, 2115 North Campus Drive,Evanston, IL 60208-2610.

Background on Food Packaging...........................T12Connecting to Your Curriculum ............................T16Module Overview ..............................................T17Module At-a-Glance ...........................................T18Using the Activities and Design Projects ................T20Flexibility of Use................................................T24

Adapting the Modules ........................................T26Inquiry and Design in the Classroom.....................T28Assessment Options ...........................................T30A Note About Safety ..........................................T32Resources on Food Packaging..............................T32

AC T I V I T I E S

DE S I G N PR O J E C T S

AP P E N D I X

Activity 1 Planning Guide .....................................1AActivity 1 ........................................................1



Activity 4 Planning Guide .....................................26Activity 4 ........................................................26



Teacher’s Edition Contents

Black-Line Masters .........................................A1Index.............................................................A23

T3

Introduction .............................................T4

Meeting Education Standards ....................T6

Other Materials World Modules.................T9

Using the World Wide Web .......................T10

US I N G YO U R FO O D PA C K A G I N G MO D U L E

Design Project 1 Planning Guide ...........................48Design Project 1 .............................................49

Design Project 2 Planning Guide ...........................54ADesign Project 2 .............................................54

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The Materials World Modules are easy to organize,inexpensive to run, and adaptable for use, in wholeor in part, with any science, math, or technicaleducation curriculum. The modules will help youenrich your teaching by:

• supplying new and exciting hands-on activitiesto supplement existing classroom and lab experiences

• incorporating science, math, writing, and think-ing skills students need to develop

• promoting an awareness of the roles science andtechnology play in society, down to the details ofour everyday lives

• introducing students to issues that materials scientists face at the forefront of technologicalresearch

• reinforcing students’ abilities to work creativelyand collaboratively

• motivating students to develop and communi-cate clear, logical explanations of phenomenathey observe

• guiding students to take increased control oftheir work, so they can successfully completeindependent, design-centered projects

• simulating the work processes of scientists andengineers, to give students a sense of whatcareers in these fields can be like

W h a t i n t h e w o r l d a r e

relate your teaching to your students’ everydayworld? The question of relevance is one your stu-dents may frequently raise. And the MaterialsWorld Modules can help you flesh out youranswer, whatever science, math, or technical edu-cation subject you teach. Each module explores atopic of current interest in materials science, com-

bining clear instruction with innovative activitiesand design-centered projects. With these modules,students make a direct connection between whatthey are learning in class and their everyday lives.The Materials World Modules will capture yourstudents’ interest and inspire their creativity.

How can the Materials World Modules help you . . .

Enrich Your Teaching with the Materials World Modules

How the Materials World Modules WorkThe Materials World Modules are built around a common structure. Four or more related Activitiesintroduce an important topic in contemporary materials science. Through these Activities, studentslearn about the topic, investigating key features of the materials that are the focus of the module.Then they use what they have learned from doing the Activities to participate in a Design Project.This project inspires students to design, build, test, and redesign a product that incorporates thematerials that are the focus of the module.

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Mater ia l s Wor ld Modu les?

Most people have never heardof materials science. But it ismaterials science that makes

our modern world possible.Without materials science,

there would be no optical fibers totransmit phone calls. We wouldn’thave computers, VCRs, and manymodern sports materials. The

glass towers thatrise above our

cities would exist onlyin the imagination,and space explo-ration would be anever-distant dream.

Materials science isan interdisciplinaryfield that employsthe tools of science,technology, andmathematics indeveloping newmaterials to meetspecific needs. In aquest to uncover

nature’s design secrets,materials scientists haveanalyzed cross sections ofdragonfly wings, examined

the microstructure ofcorals, andexperimented withthe “superglue” mussels useto attach themselves to rocks.

They then bring what they havelearned to the design and manufac-

ture of different materials. Each materialhas unique properties, which are engi-neered into the material’s physical andchemical structure. These properties allowthe material to serve specificfunctions—the smooth, hard, cleanable ceramic tiles designed for a bathroom are very different from the lightweight, heat-shielding tiles designed for the Space Shuttle.

With the MaterialsWorld Modules, students gain an in-depth view of many different kinds of materials and deal directly with issues of materials design. By introducing students to materials science through the MaterialsWorld Modules, you will give students an opportunity to understand the worldaround them in a way they’ve never experi-enced before.

Learning About the World Through Materials Science

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The Materials World Modules were designed with the following science education goalsin mind. These goals are consistent with recent National Science Education Standards* andinclude:

• Developing the abilities necessary to do scientific inquiry. These include the ability togenerate questions, design and conduct scientific investigations, formulate models, analyzealternative models, and communicate and defend explanations.

• Understanding scientific inquiry. Understanding that scientific inquiry is focused onlogically consistent explanations, grounded in current knowledge and augmented by mathe-matics and technology.

• Becoming familiar with materials science. Developing an understanding of materialsscience by applying knowledge from physical, life, and earth sciences to create materials forspecific purposes.

• Taking part in iterative design. Providing opportunities to identify technological prob-lems, propose designs, choose between alternative solutions, implement and evaluate asolution, redesign the product, and communicate the problem, process, and solution.

• Understanding the relationship between science and technology. Understanding thedifferences between the purposes and nature of scientific and technological studies and theinterrelationship between these fields.

• Understanding contemporary problems. Appreciating the use of science and technologyto meet local, national, and global challenges, including problems of personal and commu-nity health, natural resources, environmental quality, and human-induced hazards.

• Presenting a historical perspective. Viewing the history and nature of science as ahuman endeavor, producing new knowledge, supported by developing technology.

State and national standards for teaching sci-ence and mathematics mandate that studentsnot only learn facts and theories but that theyalso gain the ability to apply what they learn toreal-world situations. The Materials WorldModules can give you a clear-cut and direct way

to meet these standards. Both in their generalpedagogical approach, featuring inquirythrough design, and in their specific presenta-tion of science content, the Materials WorldModules meet current education standards atthe local, state, and national levels.

*National Research Council. National Science Education Standards. Washington, D.C.: National Academy Press, 1996.

How can you use the Materials WorldModules to meet education standards?

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Inquiry Through DesignThe pedagogical base of the Materials WorldModules can be captured in a phrase: inquirythrough design. This approach unites the abstract,quantitative methods of scientific inquiry withthe concrete methods of technological design,helping students develop and integrate theseinterlinked skills in a unique way. The chartsbelow, adapted from the National ScienceEducation Standards*, outline steps in the com-plementary processes of scientific inquiry andtechnological design.

In guiding students through the processes involved in scientific inquiry and technological design, theMaterials World Modules reinforce essential thinking, reasoning, and laboratory skills with unparalleledeffectiveness. With the Activities and Design Projects, the Materials World Modules inspire students toincrease their skills, integrate quality work habits, and enjoy learning in the process.

• Identify new or replacement uses for amaterial or technological device

• Propose designs to meet a specific needand select the most promising alternative

• Create a prototype and develop appro-priate testing procedures following rules oflogic and evidence

• Evaluate tests, redesign prototypes, andidentify constraints in designs and testingprocedures

• Communicate about the design and theprocesses of its development and evaluation

Technological Design

• Develop researchable questions to guidescientific investigations

• Design and conduct scientific investiga-tions using appropriate tools and mathemat-ical analysis

• State scientific explanations and devisemodels following rules of logic and evidence

• Recognize and analyze alternative expla-nations and models

• Communicate and defend the conclusionsof scientific investigations

Scientific Inquiry

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a group of university professors called you up andasked, “What can we do to improve science educa-tion in your high school?” Northwestern’s ProfessorRobert Chang and materials-science researcherMatthew Hsu tried it. Based on their initial phonecalls, they held meetings with more than 20 sci-ence teachers and curriculum supervisors fromnorthern Illinois and southeastern Wisconsin. Atthe meetings, teachers drew up a wish list of waysscientists and educators at Northwestern couldhelp them meet their goals.

The Materials World Modules were developedwith this wish list in mind. Teachers have par-ticipated in the design and development of allof the modules. In fact, teachers co-wrote manyof the modules together with scientists andeducators at Northwestern. The modules haveundergone extensive field-testing at a numberof high schools with hundreds of studentsparticipating.

What would you say if . . .

Teachers’ wish list

We would like to be able to:

• Offer students stimulating activities that

relate science to their everyday lives

• Use projects to motivate students and

help them apply their real-world experiences

to scientific problems

• Find practical ways to promote collabora-

tive learning in the classroom

• Close the gap between classroom science

and science on the frontiers of research

• Hook into Northwestern’s resources on

science and science education through

computer linkages

• Develop collegial support among science

teachers across the nation and scientists

and science educators at Northwestern

and other universities

The Authors

Brad Goral has taught chemistry for 15 years atNew Trier High School in Winnetka, Illinois. He focuseson interdisciplinary content and problem-based learn-ing. In addition to working on the Food Packagingmodule, Brad has participated in computational scienceprograms at Northwestern and the National Center forSupercomputing Applications at Champaign/Urbana.

Kate Heroux earned her Master of Educationdegree from the University of Manchester inManchester, England, in 1993. She has taught chemistryat Lake Forest High School for two years. One of Kate’sinterests is science articulation and integration. Katehelped write and field test the Food Packaging module.

Cindy Quinn has been a science teacher for fiveyears. In addition to working with the Materials WorldModules team, she has been a Department of Energyresearch assistant and has worked with members ofNorthwestern’s BGuILE (Biology Guided InquiryLearning Environments) Project to develop curriculumand software for science classrooms.

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Teachers have reported that students are very excited about the modules. They especially enjoy the Design Projects, in which they get to design, build, and test their very own materials or products.

The initial development of the Materials World Modules has been funded by a grant from the National Science Foundation. The project continues to expand, with the development of new modules and additional support materials. You can get involved in the design or field-testing of upcoming modules by contacting:

Program Coordinator Materials World Modules Northwestern University Evanston, IL 60208-2610

(847) 467-2489 e-mail: [email protected] website: www.materialsworldmodules.org

Biodegradable MaterialsStudents make, test, and evalu-ate biodegradable films and gels. They use their knowledge to design devices that release a dye in a controlled manner as they degrade.

BiosensorsStudents investigate the use of biological molecules as materials and use enzymes as chemical sensors in the design of diagnostic tests for peroxide, cholesterol, and glucose.

CeramicsStudents study the microstruc-ture of ceramics and simulate high-temperature synthesis of ceramics. They then use ceramics to make a voltage-protecting device.

CompositesStudents discover what com-posite materials are and test them to learn their advan-tages over pure materials. They design a new composite mate-rial to make a strong, light-weight fishing pole.

Concrete: An Infrastructure MaterialStudents learn how the com-ponents of concrete can be modified to alter the proper-ties of concrete. They use their knowledge to make concrete roofing tiles that meet specific design and performance criteria.

Environmental CatalysisStudents examine different types of catalytic systems, including heterogeneous catalysis, thermocatalysis, and photocatalysis, which they can adopt in their own designs to catalytically eliminate water pollutants.

Introduction to the Nanoscale: Inquiry into Surface Area and VolumeStudents explore how changes in the shape or size of an object affect the surface area to vol-ume ratio, which can change dramatically in the nanoscale. They apply this knowledge to design an “exploding” liquid geyser.

Manipulation of Light in the NanoworldStudents learn about how light waves interact with matter. They then apply their knowledge of diffraction and interference to fabricate, test, and evaluate their own photonic crystals.

NanotechnologyStudents investigate size-dependent properties of nanoscale materials, how they are made and characterized. They are challenged to design a prototype nanoscale imaging apparatus.

PolymersStudents examine properties of polymers. They design and test a humidity sensor made of a polymer film.

Smart SensorsStudents investigate the behav-ior of piezoelectric films. They use these materials to make a coin-counting device.

Sports MaterialsStudents test and analyze a wide variety of materials used in athletic equipment. Then they design a suitable material for use in a newly invented game.

Other Materials World Modules

Professor Robert P. H. Chang A veteran of materials research, Professor Chang worked at Bell Laboratories in New Jersey for 15 years before coming to Northwestern in 1986. As director of the Materials Research Institute and also of the Materials World Modules program, he admits, “With my research in materials science, the results come only slowly. But I get immediate rewards from directing the development of these modules: I see young peopleʼs interest in science sparked. It is among the most exciting work I have ever done.”

The Director

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Information abounds on theInternet, but it’s easy to get lost onthe electronic superhighway. Onesure place you can send studentsis to the Materials World ModulesWeb site. Here, students can finda well-maintained list of addresses(URLs) to many interesting Websites related to module topics andto materials science. We keep thislist up-to-date so you can avoidthe frustration of collecting URLsfor a particular topic only to findthe sites have moved or are nolonger in existence (a commonproblem).

Another way to help students usethe Web is by doing some trail-blazing before you send them tothe computer. The PlanningGuide pages of this module allinclude a feature called Using theInternet. This feature suggests keywords you can use to locate Websites with information about poly-mers. After you log on to theInternet, select a search engine,such as Webcrawler, Yahoo, orAlta Vista, to find Web sites thathave information on the key wordtopic. Check out some of the dif-ferent Web sites and give the

URLs of the best sites to your stu-dents. This will help students findthe most current informationquickly.

If you have questions about theMaterials World Modules Website or about ways to use theInternet for research related tothe modules, contact us [email protected]. See you onthe Net.

What wonders can you find on the Web?

For Teachers• an overview of the MWM project as a whole• an overview of each of the many modules• contact with teachers who have used the modules• links to other resources on the Internet that

reinforce or extend concepts stressed in the Materials World Modules

• assessment rubrics to help you tailor the modules to your classes• samples of students’ work • announcements of upcoming MWM conferences and workshops in your area• many publications put out by the MWM team

For Students• inspiration for their own design projects, based on ideas other

students have had • links to international resources that have information

about materials and materials science• pointers to relevant educational programs on

the Internet

Visit us at http://mwm.ms.nwu.edu/

Helping Your Students Use the Internet for Research

The World Wide Web has a wealth of informationto enhance science and math curricula. Specifically,the Materials World Modules program has a Website that can enrich your experience as you use the

modules. Students can also use our Web site as astarting point for current research on differentmaterials and their applications. The MaterialsWorld Modules Web site offers these features:

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ContentsBackground ......................T12

Connecting toYour Curriculum.................T16

Module Overview .............T17

Module At-a-Glance...........T18

Using the Activities and Design Projects ...........T20

Flexibility of Use ..............T24

Adapting the Modules........T26

Inquiry and Design in the Classroom ...............T28

Assessment Options ..........T30

A Note About Safety .........T32

Resources onFood Packaging .................T32

Using Your Food Packaging Module

The following section providesa variety of information to helpyou use the Food Packagingmodule with ease.

Background The Background sec-tion gives you general informa-tion about food packaging,which you can share, if you wish,with interested students.

Connecting to Your Curriculum Thissection can help you decide howto fit the Food Packaging moduleinto your curriculum, whateversubject you teach. Connections(brief teaching tips in the marginnotes) are also listed for varioussubjects.

Module Overview The brief sum-maries of the Activities andDesign Projects provided in theModule Overview are a furtheraid to planning.

Module At-a-Glance This chartlists learning objectives, materi-als, and estimated time for eachof the Activities and DesignProjects.

Using the Activities and DesignProjects This section points outthe features in the StudentEdition of the module and high-lights how you can use the differ-ent features to help students further their learning.

Flexibility of Use Addressing theissues of time, teaching style, andteaching students of varying abil-ities, this section gives tips tohelp you use the modules what-ever your goals or constraints.

Adapting the Modules This sec-tion gives further tips on differ-ent ways you can adapt the mod-ule for particular classes or forparticular pedagogical goals.

Inquiry and Design in theClassroom This section gives tipson incorporating elements of sci-entific inquiry in the module andon running successful DesignProjects.

Assessment Options A variety of assessment options is outlinedfor the module, includinginquiry-based assessments, traditional assessments, self-assessments, and portfolio assessments.

A Note About Safety Specificsafety tips help you run the mod-ule successfully and safely.

Resources on Food Packaging Anannotated list of books, articlesand Web sites related to themodule topic can help youand your students learn more.Additional Internet resourcescan be found by visiting theMaterials World Modules Website, http://mwm.ms.nwu.edu/

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Background on Food Packaging

A hiker stops to rest beside a trailand takes a box out of her back-pack. Inside the box is a tray offood—the hiker’s dinner. Insteadof building a fire or lighting acamp stove to heat her meal, how-ever, she simply removes anothertray from the box. This mealcomes with its own “stove”—aspecially designed heating traythat produces heat through achemical reaction. The hungryhiker simply opens a packet ofwater (included in the package)and pours it on the heating tray.Inside the tray is a plastic pad,which contains magnesium, aniron alloy, and salt. When water isadded, salt water forms. The saltwater rusts the metal in the pad,and heat is produced. Fifteenminutes later, the hiker sits downto a steaming, hot meal.

Food packaging has come a longway from the woven baskets andclay pots that our early ancestorsused to store and carry their pro-visions. Although the basic pur-pose of food packaging remainsthe same—to contain and protectfood until it’s eaten—today’spackaging often does much more,as the example of the “heatermeal” shows.

Food packaging plays many roles.It keeps food safe to eat and pro-tects it from damage. It makesfood easy to handle for shipping,storage, and display. It providesinformation and offers conve-nience to consumers. It also offersmany benefits, including less foodwasted due to spoilage or damageand fewer food-related illnesses,

because of the reduced spread ofdisease-causing microorganisms.

Food packaging technologyresponds to society’s changingneeds. In the U.S. and othercountries, for example, an in-crease in the number of smallerfamilies and single-personhouseholds has led to new devel-opments in packaging for conve-nience foods, carry-out items, andsingle-serving meals. An increaseddemand for health foods has ledto innovations in packaging freshfruits and vegetables. New tech-nologies for preparing foods, suchas the microwave oven, have ledto new types of packaging as well.Increased concerns about theenvironment and the ecologicalimpact of packaging and legisla-tion, such as “bottle bills,” havealso put pressure on manufactur-ers to produce packaging thatcan be recycled or that is bio-degradable.

Designing Food Packaging Food packaging designers beginby looking at the physical andchemical properties of the food tobe packaged. They must considerwhat kind of protection the foodneeds and how the package willbe manufactured, shipped, stored,displayed, used, and disposed of.In addition, they must meet thefood manufacturer’s production,marketing, and cost specifications.

Packaging designers then choosefrom a number of materials,including paper, cardboard, glass,metal, plastic, and composites,from which to construct the pack-aging. To design new packaging,packaging designers often usecomputer-aided design (CAD)systems. Using CAD, a designercan draw a design on-screen orscan in images from other sources,such as sketches, photos, orvideo. The computer then pro-duces a wireframe model—athree-dimensional diagram of the

Meals heated by chemical “stoves” were first developed for use by the U.S. military inthe early 1990s.

The majority of food packaging waste ends up in landfills.

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packaging that can be viewedfrom different angles, overlaidwith graphics and text, andredesigned with the touch of afew buttons. The computer caneven be set up to provide infor-mation about the physical charac-teristics of a package, such as itscapacity, weight, and strength.Using such a program, a designercan quickly see how designchanges will affect these charac-teristics.

New materials and new applica-tions of existing materials have ledto exciting innovations in foodpackaging design. For instance,fresh vegetables need to “breathe”to stay fresh and flavorful. As theyripen, these foods take in oxygenand give off carbon dioxide. Ifthey don’t get sufficient oxygen orif too much carbon dioxide buildsup in the package, the vegetablescan mold or rot. To package freshvegetables, materials engineershave developed plastic film pack-aging with tiny holes that allowoxygen to enter and carbon diox-ide to escape, while also retainingneeded moisture. They’ve evendesigned packaging that willbreathe at different rates, matchedto the specific needs of the food.

Food Packaging and theEnvironmentBut we pay a price for all thispackaging—waste. About 35% ofmunicipal solid waste—wastefrom homes, businesses, and insti-tutions, such as schools, and hos-pitals—is packaging waste. That’s72 million tons a year, and abouthalf of that is food packagingwaste. Much of that waste endsup in landfills, many of which arerapidly filling up.

Food packaging waste was notalways such a problem. As one

environmental advocate puts it,“For centuries, the business of eat-ing did not contribute all thatmuch to the waste stream—whatwas added was generally decom-posable or compostable materialslike corn husks and pea pods.”

Today, though, with hundreds ofconvenience foods and single-serving packages made of non-biodegradable and nonrecyclablematerials, we produce a lot ofpackaging waste. How can wereduce the impact of food packag-ing on the environment? One wayis to use less packaging—a con-cept known as source reduction.Using less packaging means thatfewer materials and energyresources are used to manufacture

Over the past few decades, Americans havedramatically increased their use of conve-nience foods, such as frozen microwaveablemeals. Since many of these foods are pack-aged in nonrecyclable and nonbiodegradablematerials, their use has contributed to anincrease in food packaging waste.

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packaging and less waste is pro-duced when the packaging is dis-posed of.

A number of packaging manufac-turers have turned to lightweight-ing—reducing the amount ofmaterial used in a container—as away to reduce packaging and cuttheir costs. For example, they’vedeveloped new plastics that canbe made into ultra-thin-walledcontainers. Such containers useless plastic and thus cost less,without sacrificing importantproperties, such as stiffness andstrength. Aluminum beveragecans have also gotten thinner andlighter, and as a result take lessaluminum to manufacture. In1972, 1 kg of aluminum pro-duced only 48 cans. Today 1 kg ofaluminum yields 70 cans.

Such changes in packaging canmean substantial savings for man-ufacturers. A pasta company, forinstance, switched from poly-styrene trays inside shrinkwrapped,plastic-coated paperboard cartons

to polyethylene bags for its frozenpasta. This resulted in a 475-ton-per-year waste reduction and a50% cost savings. The change inpackaging also meant that morebags could be shipped in eachcorrugated shipping box, reduc-ing the use of corrugated card-board by 33%.

Using recycled or recyclable mate-rials also helps reduce waste.Paper, cardboard, glass, and alu-minum are all widely recycled andused as materials in new foodpackaging. Plastic recycling, how-ever, is more limited. Althoughsome plastics are currently beingrecycled into products with non-food uses, recycling plastic forfood use presents some problems.One obstacle to “closing the loop”on plastic recycling—using recy-cled plastic food packaging tomake new plastic food packag-ing—has been FDA concernsabout food safety. Plastics may becontaminated by a number ofsubstances, such as adhesives,

Unloading cans at an aluminum recyclingcenter. Currently in the U.S., more than60 percent of aluminum beverage cansare recycled.

pigments, dirt, paper, metal, andfood waste. These contaminantsmay remain in the recycled plasticand potentially migrate into foodpackaged in recycled plastic. Newtechniques are being developed,however, that allow the use ofmore post-consumer recycledmaterials without compromisingsafety or quality. For example, onecompany has come up with amethod of using 100% post-con-sumer recycled polyethyleneterephthalate (PET) for fresh pro-duce packaging. Because singlematerials are easiest to recycle,engineers are also working onnew techniques for making single-material containers, such asimprinting information directlyon plastic containers rather thanon paper labels.

Reusable containers can also helpkeep waste in check. In manyEuropean countries there are strictwaste management guidelines,and as a result, reusable packag-ing has become a popular option.For instance, in Germany, about75% of Coca-Cola’s glass and plas-tic bottles are refilled.

Another way to reduce waste fromfood packaging is through com-posting. According to a 1992study by the National AudubonSociety/Procter and Gamble Co.,70 percent of household trashcould be removed from landfillsby composting and recycling.Since materials contaminated by

food wastes cannot currently berecycled, composting is a promis-ing option for biodegradable foodpackaging. One British companyhas developed a biodegradablepolymer through the fermentationof glucose. This material could beused instead of plastic as a water-proof coating for paper and card-board. Once used, the entire con-tainer could be composted.

Reducing food packaging wastehas a number of environmentalbenefits. It reduces waste overalland conserves resources, includ-ing energy and land that wouldbe needed for new landfills.

A number of new developmentsin food packaging clearly takethese environmental concerns intoaccount. Biodegradable polymersmade of corn, wheat, or potatostarch mixed with cellulose holdpromise as replacements for sometypes of plastic packaging. Andsomeday we may even be able toeat the packaging that protectsour food. One company is usingcollagen, a fibrous protein, to pro-duce a packaging film. When foodwrapped in the film is cooked, thefilm melts right in.

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Some companies are working on methods for using post-consumer recycled plastics toproduce new plastic food packaging like this.

The Food Packaging module can enhance your curriculumand increase your students’ understanding of science and technology. The chartsbelow list subjects that dovetail well with the Activities and Design Projects in thismodule. Connections (specific teaching tips) for the subjects are listed along withpage references.

Mathematics

Computer ModelingFormulasGraphingPercentagesRatesRatiosVolumeWeights and Measurement

Biology and Life Science

BiodegradationDecomposersEnvironmental IssuesMicroorganismsPlant HormonesThermoregulatory Adaptations

Chemistry

Acids and BasesBondingChanging States of MatterHeat and TemperatureKinetic Energy of MoleculesPolymersProperties of Matter

Geology and Earth Science

MiningEarth Science Connection p. 7

Connecting to Your Curriculum

Biology Connectionspp. 12, 13, 18, 22, 43

Physics and Physical Science

AccelerationForcesGravityHeat and Heat TransferInsulationMassMicrowavesNewton’s Second Law of MotionPotential and Kinetic EnergyThermal EnergyVolume and Capacity

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Mathematics Connections pp. 3, 11, 16,

17, 22, 25, 44, 45

Technical Education

Insulating MaterialsMicrowave Ovens

Social Studies

History of Food Preservation andPackaging Technology Social Studies Connection p. 10

Language Arts

Describing a SequenceLanguage Arts Connection p. 29

Physics Connections pp. 31, 34, 47

Chemistry Connections pp. 8, 15

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Through the following Activities, students learn about thefunctions of food packaging and the properties of food packaging materialsas well as the impact of these materials on the environment. Each Activity pre-pares students for the Design Projects, in which they are challenged to designand build a package for a hot potato and new type of food packaging.

Food Packaging Module Overview

Design ProjectsActivities

1 Designing aHot Potato PackageStudents design prototypes of apackage for a baked potato thatwill keep the potato above aspecified temperature for aspecified period of time, protectthe potato from physical dam-age, and meet weight, size, andcost specifications. Students testand evaluate their prototypesand then improve their bestpackage design for anotherround of prototype testing.

2 Designing New FoodPackagingStudents design a new type ofenvironmentally friendly foodpackaging. They can improveexisting food packaging ordesign packaging for a newfood product. Students con-struct, test, evaluate, andredesign prototypes of theirpackaging to determine thebest design.

1 InvestigatingFood PackagingStudents take apart a package ofmicrowave popcorn, identifythe purposes of each part of thepackage, examine the materialsfrom which they are made, anddraw conclusions about thepackage’s design and the rea-sons for the choice of materialsused.

2 Analyzing FoodPackaging MaterialsStudents look for different kindsof food packaging, identify thematerials used in the packaging,list the purposes of these mate-rials, analyze the properties ofthe materials, and formhypotheses about why eachmaterial was chosen for its use.

3 Evaluating the Impactof Food Packaging onthe EnvironmentStudents examine several differ-ent types of packaging for thesame food product. They com-pare the mass of each packagewith the amount of food pack-aged to determine which pack-aging alternatives produce theleast amount of waste.

4 Researching FoodPackaging Materials Students try to come up withan environmentally friendlyresponse to the question “Paperor plastic?” Students researchthe manufacture, use, and dis-posal of paper and plastic gro-cery bags and draw conclu-sions about the overall environ-mental impact of each material.Students write a researchreport summarizing their find-ings.

5 Designing aProtective PackageIn Part A, students test andcompare the ability of differentpackaging materials to protectpackage contents—in this case,a tomato—from a fall. In PartB, students use what they havelearned to design, construct,and test a package that protectsa tomato, while not exceedingcertain mass specifications.

6 Comparing theInsulating Properties ofPackaging MaterialsIn Part A, students test andcompare the insulatingproperties of different packag-ing materials. In Part B, stu-dents use what they havelearned to design, construct,and test an insulating package,while not exceeding certainsize specifications.

SafetyDiscuss safety issues students should be aware of, including:

• getting a parent or guardian’s permission to visit a grocery store to gatherdata for the activity

• letting the grocery store manager know students’ purpose in visitingthe store so as not to arouse suspicion as they examine different foodpackages

• safety issues that may be of concern in your classroom or in stores in stu-dents’ neighborhoods

6A F o o d P a c k a g i n g

PLANNING GUIDEAnalyzing FoodPackaging Materials

PurposeTo identify and analyze materialsused in food packaging in terms oftheir purposes and properties.

Summary of the ActivityStudents look for different kinds offood packaging, identify the materi-als used in the packaging, list thepurposes of these materials, analyzethe properties of the materials, andform hypotheses about why eachmaterial was chosen for its use.

Advance PreparationYou may wish to bring studentson a field trip to a large, well-stocked supermarket where theycan do Part A of the activity. Ifso, arrange your trip in advance,informing the store managementof the visit and its purpose andgetting the manager’s permis-sion. Some stores may be willingto give the class a behind-the-scenes tour to show students thekinds of packaging food is inwhen it arrives off the truck.

urriculum onnectionsC

DD

L INKSTO THE PREVIOUS ACTIVITY In Activity 1, students made a detailed exami-

nation of a microwave popcorn package to determine the materials

of which it was made and the purpose of each material. They build

on that experience in this activity by analyzing the materials used in

a variety of food packages.

TO THE NEXT ACTIVITY In this activity, students identify properties of

food packaging materials and how they are used. In Activity 3, stu-

dents will investigate the environmental impact of food packaging

materials by looking at the amount of waste produced when they are

discarded.

TO THE DESIGN PROJECTS The Design Projects challenge students to

design new food packaging, and this activity familiarizes them with

the properties of common food packaging materials that they may

choose to use in their prototypes.

2ACTIVITY

Connecting to Your Curriculum on page T16 suggests ways you can fitthe Food Packaging module into your general curriculum. The chart atright gives ideas for connecting concepts introduced in this activity withdifferent disciplines. The page numbers in the chart refer to teaching tipsthat you can use to make connections to the subjects listed.

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Packaging materials—primarily paper, cardboard, glass, plastic, steel, andaluminum—are made into boxes, cans, jars, bottles, bags, and other contain-ers and used to package foods during shipment, storage, display, and con-sumer use. As students will observe in this activity, food packages have manydifferent purposes, including protecting the food until use, preventing spoilage,providing convenience, complying with government regulations, communicat-ing information, and attracting consumers.

One issue that arises with food packaging is the question of overpackaging.You’ve probably seen dozens of examples of food packaging that seemsexcessive, for instance, slices of cheese individually wrapped in plastic or indi-vidual servings of lunch meat, cheese, and crackers in a plastic tray coveredwith shrink wrap and packaged in a cardboard box. Some packaging thatappears unnecessary may help reduce waste overall because it keeps foodfresh and safe to eat longer. But some packaging is designed simply to con-vince consumers that they are getting something of value or convenience, sothat they will buy the product. In general, overpackaging is considered to bepackaging that is not necessary for storing a product, protecting its shelf life,or communicating essential information.

ArtGraphic design

BiologyMicroorganisms p. 12Plant hormones p. 13

ChemistryAcids and bases p. 15Polymers p. 8

MathematicsPercentages p. 16Graphing p. 11

Earth SciencesMining p. 7

Home EconomicsFood storage

Social StudiesHistory of food preservation and

packaging technology p.10

Background In format ion

ortfolio ProjectAt the completion of this activity, have each student select a favorite food anddesign a better package for it. Have students draw or even construct the improvedpackage and include the drawing or prototype in their portfolios.

PP

A c t i v i t y 2 A n a l y z i n g F o o d P a c k a g i n g M a t e r i a l s 6B

Cross-Curricular TeachingInvite an art teacher to visit theclass and discuss how text andartwork are produced and printedon food packages. With the artteacher, students can comparethe graphic design of severalcommon food packages, forinstance cereal boxes, juice con-tainers, or canned tomatoes. Theymight analyze the art and typethat appear on the packages anddescribe how the graphic designmay influence consumers.

U s i n g t h e I n t e r n e tTo learn about food packaging

materials, go to an Internet searchengine and use the key words

food packaging.

2INTRODUCTION

In Activity 1, you examined the materials used in one type of foodpackaging—a microwave popcorn bag. In this activity, you’ll analyzethe materials used in a number of different types of food packaging.

Food PackagingMaterialsWhen you think of food packaging, you might picture a canister full of

potato chips or a plastic jug of milk. But not all food packaging ismanufactured. Consider the coconut, for example. This fruit of thecoconut palm is actually a beautifully designed, natural package. Thehard shell protects the delicate contents inside: a seed and the food

needed to nourish it as it begins to grow. Like the coconut, most freshfoods come in their own protective packages. Egg shells, nut shells, and theskins of fruits and vegetables all preserve and protect what’s inside them.

Early humans probably took their cue from the world around them andbegan using natural containers, such as seashells, gourds, and animalskins, to carry and store foods. Later, people put other natural materialsto work, carving wood into bowls and weaving plant fibers intobaskets—probably the first examples of human-made food packaging.

Many types of materials are used in foodpackaging. The choice of materials dependson the purpose of the packaging and theproperties of the materials.

CONCEPTSbehind

FOOD PACKAGING

1500 B.C.Artisans in Egypt makeglass bottles and jars.

600 B.C.Ancient Greeks and Romansuse wooden chests, kegs,and barrels for food storage.

7000 B.C.Clay pottery is used inCatal Huyuk, a settlementin what is now Turkey.

200 B.C.Chinese invent wrappingpaper, made from sheetsof mulberry bark.

Pottery from 3500 B.C.

1500 B.C.

6 F o o d P a c k a g i n g

1000 B.C. 500 B.C. 0

Natural food packaging—a coconut

To Inspire Questioning and LearningAsk several students what they had forbreakfast today or for an evening meal lastnight, and write each food on the board.Then ask students to name the kind of pack-age each food came in, be it a “natural” pack-age such as a nutshell or banana peel or amanufactured package such as a pasta orcereal box. Have students briefly discuss thepossible purposes of each kind of packaging.

Focusing on Study SkillsConcepts Behind Food Packaging summa-rizes the main point of the activity. Writethis summary on the board for students torefer to as they read the introduction and dothe activity.

To sharpen students’ research skills, havethem learn about other developments in thehistory of food packaging and add these to aposter-sized illustrated timeline.


ulticultural LinksAround the first centuryA.D., Syrian glassworkersmade an important discov-ery. They developed a tech-nique for blowing glass intohollow shapes. This innova-tion allowed artisans to cre-ate a wide variety of glasscontainers for all types offood storage.

MM

A c t i v i t y 2 A n a l y z i n g F o o d P a c k a g i n g M a t e r i a l s

Over time people developed other materials, with otherproperties, for food packaging, as the timeline below shows.Pottery, glass, cloth, wood, and paper were among thematerials most commonly used.

Metals, too, were used for food storage for thousands of years.But it wasn’t until the early 1800s that the technology formaking tin cans was developed. In 1809, the French generalNapoleon Bonaparte offered a reward to anyone who coulddiscover a way to preserve food for his army to eat on longcampaigns away from home. A French chef came up with thewinning idea: he packed the food in glass jars, using heat tosterilize the contents. The following year a British inventorpatented the use of tin cans instead of glass jars. These all-purpose containers, actually made of tin-coated steel, quicklybecame popular. Food preserved in tin cans remained safe toeat for years, without refrigeration.

The Industrial Revolution, which began in England in the late18th century and then spread around the world, also broughtchanges in food packaging. As economies shifted fromagriculture to manufacturing, people left the farms and movedto cities to work in factories. With fewer people living nearfood-producing areas, food had to be shipped farther andstored longer. Manufacturers began using paper andcardboard cartons to package foods. These containers werelightweight and easy to ship and store. In addition, advertising

7

A.D. 1890sFirst printedcardboardcartons.

A.D. 1933–35Polyethylene andpolystyrenedeveloped.

A.D. 1810First tin cans.

A.D. 1949First plastic bag.

A.D. 1959First aluminum can.

A.D. 1800 A.D. 1850 A.D. 1900 A.D. 1950 A.D. 2000

Tin can from 1853

Cardboard packagingfrom the early 1900s

Note on Food PreservationThe invention of canning in 1809 is creditedto the Frenchman Nicholas Appert. Appert’sprocess included heating glass jars of food inboiling water and sealing them airtight withcorks and wire. While Appert’s processingand packaging methods were generally suc-cessful, spoilage still occurred. Appert attrib-uted food spoilage to air rather than to bacte-ria. Fifty years later the work of fellowFrenchman Louis Pasteur would correctlylink food spoilage to the growth of microor-ganisms. Apparently Appert’s canningprocess did not always kill the microorgan-isms that were in the food.

Note on the History of Food PackagingOne of the most common food packages isthe cardboard box. It first appeared on mostgrocers' shelves in 1899. In that year, theNational Biscuit Company, now known asNabisco, introduced a new product—a sodacracker called Uneeda Biscuit. Crackers, likemany other food products of that time, wereusually sold in bulk from barrels or large

boxes. Unfortunately, crackers sold in bulkwould often break or absorb moisture andbecome stale. The manufacturers of UneedaBiscuit wanted a package that would protecttheir product from these problems. Theydesigned a machine that would fold a pieceof paperboard into a six-sided carton. Thecarton was lined with wax paper for addedprotection against moisture and breakage.The printed paper outer wrap of the cartoncontained this message:

To protect, preserve and deliver to the con-sumer our new and splendid Uneeda Biscuit,as fresh and crisp as when just from theoven, we have devised this moisture proofpackage. Carefully remove the wrapper andafter the biscuits are eaten, you have aschool children's lunch box. Keep the boxclosed. This preserves the crispness.

The product was an overnight success, duein no small part to its unique and resourcefulpackaging. Soon other products such as but-ter, flour, and tea moved from the barrel tothe paperboard carton.

A c t i v i t y 2 A n a l y z i n g F o o d P a c k a g i n g M a t e r i a l s 7

Aluminum is the most abun-dant metallic element inthe earth's crust. Becauseof its chemical nature it isfound only as a compound,not in its pure metallic form.Bauxite, which is a mix-ture of hydrated aluminumoxides, is the principalsource of aluminum. Havestudents find out wherebauxite is found and how itis mined.

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ulticultural LinksDifferent cultures havedeveloped ingenious, multi-purpose food packages usingmaterials readily at hand.For instance, in Japan, driedfish is traditionally wrappedin a length of straw rope.This wrapping protects thefish and allows just the rightamount of air to circulate tokeep the fish safe to eat forsix months or longer.Another advantage to thispackaging: the fish can beunwrapped a little at a timeas it is used and the packagecan be resealed by simplyrewinding the rope.

MM

could be easily printed on paper packages—an advantage forfood manufacturers trying to win new customers.

Supermarkets, which first appeared in the U.S. in the 1930s,led to further innovations in food packaging. Before this time,most people shopped at general stores where foods, such asflour, sugar, and crackers, were kept in barrels and scooped upby the shopkeeper into containers that customers brought fromhome. With the arrival of self-service supermarkets came theneed for new types of packaging. One material in particularbegan to fill this need—plastic. Plastic packaging waslightweight, relatively cheap, and virtually unbreakable.

In the last 30 years, other changes in society and technologyhave created a number of new packaging needs. An increaseddemand for convenience foods, for instance, has led to ready-made meals and snacks in packages designed to go from thefreezer to the microwave to the table. These packages are oftenmade of composites—a combination of materials, which arebonded together.

Today food packaging is big business—a $110 billion-a-yearindustry in the U.S. alone. In this activity, you’ll take a closerlook at some of today’s food packaging materials and howthey’re used.


In a general store (left), many foodswere sold in bulk—the shopkeeperscooped them up from big barrels intocustomers’ reusable containers. Today(right) most foods are packaged in indi-vidual packages, so shoppers can servethemselves.


Plastics are polymers, madeup of smaller units calledmonomers. Different plasticshave different properties. Forexample, polyvinyl chloride(PVC) begins to soften atabout 70–80ºC, while poly-propylene (PP) remains solidup to about 145–150ºC. PVCis also a good oxygen barrier,while PP lets oxygen passthrough it. These propertiesare determined by the typesof monomers that make upthe plastic, the bondsbetween monomers, andother chemicals, such asplasticizers, that are added tothe plastic. (Plasticizers aresubstances that prevent theformation of some of thebonds between polymer mol-ecules, which makes theresulting plastic more flexi-ble.) Common monomersused in plastic productioninclude ethylene, propylene,benzene, and styrene. Havestudents investigate one ofthe plastics commonly usedin food packaging and dia-gram its chemical structure.

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Note on the History ofPackaging MaterialsPlastic was first made in 1868 by JohnWesley Hyatt, an inventor who was trying tocreate a material that could be used insteadof ivory to manufacture billiard balls. Hyattmixed pyroxylin (made from cotton andnitric acid) with camphor to get celluloid,the first plastic.

Tips from the Trenches

To focus students’ attention on the advertisingon food packages, I bring in brand-namegoods and matching generic items and do ablind taste test. With many foods, studentsthink that the generic item is one of thebrand-name goods. They are often quite sur-prised. They usually realize that generic prod-ucts are more economical, but without tastingthem assume that they are not as palatable asbrand-name products. The taste test alertsthem to the subtle powers of advertising onfood packaging labels.

Cindy QuinnScience teacherOak Park and River Forest High School

Take a close look at what’sinside your grocery bag. Youmight find a loaf of breadwrapped in cellophane, adozen eggs in a cardboardcarton, potato chips in a bagmade of plastic and foil, hotsauce in a glass jar, or apackage of meat on apolystyrene foam tray shrink-wrapped in plastic film. Whyare different foods packaged in such different ways? You’ll tryto answer that question in this activity.

2Analyzing FoodPackaging Materials

ACTIVITY


Think about these questionsas you do the activity:? What are the purposes of

food packaging?? Why are certain materials

used in certain types offood packaging?

? What are the propertiesof different foodpackaging materials?

Howdoes the type of foodpackaged affect thechoice of materials usedin its packaging?

esign ConnectionD

In this part of the activity, you’ll look at different types of foodpackaging, determine what purposes the packaging serves,and identify the types of materials used in the packaging. InPart B, you’ll consider the properties of those materials andform hypotheses about why certain materials are chosen forcertain types of packaging.

Make a data table with room to record:• the type of food packaged• a description of the packaging• the purposes of the packaging• the materials used in the packaging• the purposes of each material

Part A

▲


Activity ObjectivesStudents will:

• examine a variety of dif-ferent types of foodpackaging

• identify the materialsused in food packaging

• determine the purposesof the materials used inspecific food packages

• analyze the properties ofdifferent food packagingmaterials

Suggested GroupingGroups of three or four

Homework assignment maybe done individually.

Leading In to the ActivityBring in several examples of food packages.As a student reads the introductory para-graph on this page aloud, display the pack-ages on a table or desk. As a class, discussreasons why packaging engineers might havedesigned the packaging for each food.

Recording Data and ObservationsActivity-Log Sheet 2 contains space for stu-dents to list and describe foods and theirpackages, as well as list packaging materials

and their purposes. You may photocopy thislog sheet and distribute it to students, makean overhead transparency of the log sheet forstudents to copy, or have student devisetheir own data tables.

Materials (per student)• data tables in notebooks or on clipboards

• pens or pencils

• graph paper

Part A

Estimated Time• Part A, hunt done as homeworkover one or two days; 20 minutesto make group list of packagingpurposes

• Part B, 20 minutes to make groupdata table and graph; 20 minutesfor discussion

Procedure, Data, andObservations

1. Be ready to offer suggestions to stu-dents who cannot think of threeexamples in each food category.Other fresh foods might includemeats, fish, and shellfish. Other sta-ples could include sugar, honey,crackers, popcorn, and coffee or tea.Prepared foods might includemicrowave-ready meals and snacks,frozen desserts, and toaster foods.Other take-out foods include sub-marine sandwiches, pizza, falafel,tacos, burritos, ice cream, and frozenyogurt. Beverages might include cof-fee, tea, lemonade, powdered drinkmixes, sports drinks, and milk-shakes.

2. Students should perform steps 2through 4 for each package in turn.Encourage students to start withfoods that they already have athome. If possible, students shouldopen packages so that they can iden-tify all the materials used. Suggestthat if they open any packages, theycarefully store the food, so that itwill not be wasted.

If students go to a supermarket, sug-gest that when students first enterthe store, they go to see the storemanager and ask for permission toconduct their hunt in the store. Thatway, students are less likely to bequestioned by store personnel asthey handle and discuss variouspackages. Remind students to record

all the packaging materials they canobserve, without opening or damag-ing any of the packages. Studentsshould collect all the data for onepackage and then move on to thenext package.

If students go to a supermarket, sug-gest they work in pairs in the storeso that one person can examine apackage and the other person canrecord all observations.

3. Remind students that most packag-ing meets a number of different pur-poses. Refer them back to Activity 1and the many purposes they identi-fied for the microwave popcornpackage.


Procedure, Data, and Observations1. In your data table, list three foods in each of the following

categories:• fresh foods, such as fresh fruits, vegetables, and breads• staples, such as flour, dried pasta, rice, cereal, and beans• prepared foods, such as frozen foods, canned foods, and

mixes for baked goods• take-out foods, such as fried chicken, burgers, and fries• beverages, such as milk, juice, and soft drinks

2. Hunt for the foods on your list—at home, in the super-market, or elsewhere. Take your data table with you soyou can record your observations about the packagingmaterials. For each food on your list, write down adescription of the packaging. (If there are several differenttypes of packaging available for the food, describe the oneyou or your family usually buys.)

3. Describe the purposes of the packaging. Consider how thepackaging meets needs in each of the categories listed inthe chart below.


Protection Manufacturing,Shipping, and

Storage

• to keep food fromspoiling

• to keep food frombreaking

• to keep air ormoisture in or out

Use

Sample Purposes for Food Packaging

Disposal Marketing

• inexpensive• lightweight• easy to stack

• to keep foodhot or cold

• to cook in

• to be recyclable• to be reusable• to be biodegradable

• to provide roomfor printedinformation

• to appeal toconsumers

Archaeologists often findfood containers amidst theother artifacts of ancient cul-tures they uncover. Havestudents choose an ancientculture and find out whattypes of food containers theyused. Encourage students touse photos, drawings, andtext to make a visual displayof the food packaging tech-nology of the culture theyhave studied.

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Interpretations of the Data1. How many packages listed in your data table were made

of paper (including cardboard)? Glass? Steel? Aluminum?Plastic? A composite of several materials?

2. How many packages were made of materials that can beeasily recycled? How many packages could be reused?

Reflections3. Were you surprised by any of the purposes of the

packaging you examined or the materials used in thepackaging? Explain.


Packaging iscrucial. It’s thesilent salesman.Observation from anAmerican packaging designfirm

11

4. Determine the materials that are used in the packaging andthe purpose of each material. Record this information inyour data table.

5. Share your results with other group members. Make agroup list of all the purposes food packaging can serve.

Why are certain materials chosen for certain types of foodpackaging? In this part of the activity, you will discuss yourresults from Part A with other group members. Based on yourdata and group discussions, you will form hypotheses about theuses of different food packaging materials.

Make a group data table with room to record:• the materials used in the food packaging you examined• the properties of those materials

Part B

▲

4. Once students have identified thematerials that make up each package,they should look over the purposesthey have listed for the packagingand try to infer from the constructionof the package and from their knowl-edge of materials which materialserves which purpose. Some materi-als may serve the same purpose. Forexample, a plastic cap and an alu-minum foil seal under the cap bothhelp keep food fresh and help securefood in the package.

5. Ask students to refer to their datatable entries from step 3.


D I S C U S S I N G T H E Q U O T E

Have students consider howpackaging can sell a product(convenience, appealingappearance, advertisingprinted on it). For discus-sion, you might bring inthree examples of packagingfor one product, such ascereal or potato chips, andask students which one theywould buy and why.

Interpretations of the Data1. Answers will depend on students’

food choices. You might suggestthat students create a tally chart inwhich they list each material. Theyshould then look back at their datatables and count the number ofpackages in which each materialwas used. In general, paper (includ-ing cardboard) will probably be themost common packaging materialwith plastic a close second. Glassand metals (primarily steel and alu-minum) will probably be less wide-ly used.

2. Discuss the materials that can berecycled in your community. Mostcommunities have recycling pro-grams for aluminum. Some also

have recycling programs for glass,tin cans, some plastics, and paperand cardboard that are not contami-nated by food wastes. Have studentscalculate the percentage of the pack-ages they examined that can berecycled by dividing the number ofrecyclable packages by the totalnumber of packages.

Reflections3. Students may have been surprised

by less-obvious purposes, suchas protecting food during shippingor being easy to display on a storeshelf. Students may have beensurprised to find how many differ-ent materials may be used in onepackage.

Suggest that students countthe different materials usedfor each category of food list-ed on page 10 (fast food,prepared food, and so on)and determine which materi-al is most commonly used inthat category. Ask studentsto decide the best way topresent their informationgraphically and to use theirgraphs to explain theirresults to the class.

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Recording Data and ObservationsActivity-Log Sheet 3 includes a groupdata table for students to record thematerials they found in food packagingand the properties of those materials. Italso provides a graph grid for studentsto graph their data in step 2 of the pro-cedure. Photocopy the log sheet for stu-dents, or have them devise their owntables for compiling this information.

Materials (per group)• data tables from Part A

• Activity Log-Sheet 3 or graph paper

• pens or pencils

Procedure, Data, andObservations

1. Suggest that each group select onemember to record the observationsof the group and one member to bediscussion leader.

2. In this step, students pool their datafrom Part A, Interpretations question1 on page 11. Students should firstcollect data in a table and then graphit. Suggest that they make the x-axisof their graphs the type of packagingmaterial (glass, aluminum, steel,plastic, paper, and composite) andthe y-axis the total number of pack-ages made of each material. Forpackages that are not composites,but are made of more than one mate-rial, students should identify the pri-mary packaging material and countthe package in that category.

Part B


Two main categories of foodpreservatives are used today:antimicrobials (which pre-vent the growth of micro-organisms) and antioxidants(which prevent oxidationand therefore discolorationand spoiling). Have studentsfind out how microorgan-isms and oxidation harmfoods and how each of thesepreservatives works to pre-vent this damage. By law,package labels must say notonly what preservatives havebeen used but also what theydo. Have students checkpackage labels for preserva-tive information and catego-rize each preservative aseither an antimicrobial or anantioxidant.

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Interpretations of the Data1. Students will pool their data from

Part A, Interpretations question 1.Answers will depend on the foodsthat students examine. They willprobably find that paper and plas-tic are the most common materialsand that glass and metals are lesscommon. Students’ explanationsshould relate the most commonlyused material to the propertiesthat make it so suitable for foodpackaging.

Reflections2. Students may have been surprised

by which materials are most wide-ly used in food packaging.

Putting It All Together1. Students will combine informa-

tion from Part A (purposes of


Sample Properties of Packaging Materials• can be printed on• good insulator (keeps hot

things hot and cold thingscold)

• microwaveable• recyclable• reusable• biodegradable• inexpensive

• strong• breakable• lightweight• watertight• airtight• transparent• opaque (keeps light out)• can withstand high

temperatures

Procedure, Data, and Observations1. In a group data table, list all the materials used in the food

packaging that group members analyzed. Through groupdiscussion, identify the properties of each material andlist these in the group data table. A list of some of theproperties of packaging materials appears below. Be sureto consider properties that might be advantageous as wellas disadvantageous in food packaging. For example, paperis lightweight, but tears easily when wet. Glass is watertight,but shatters when dropped. To help you determine theproperties of different materials, look back at your datatable from Part A in which you listed the purposes of thematerials used in the packaging you examined.

2. Compile all the information from group members’ responsesto question 1 on page 11. Make a bar graph in which youcompare the frequency of use of the different materials.

packaging) and Part B (propertiesof packaging materials) to deducewhy a particular material or combi-nation of materials is used in pack-aging a food.

2. Sample generalizations: Fresh foodsare often packaged in plastic orpaper. Transparent packaging, suchas plastic and cellophane, lets con-sumers check the condition of thefood. Insulated plastic containers areoften used to keep fresh foods hot orcold. Paper and breathable plasticslet fresh foods “breathe.” Staplesare usually packaged in moisture-resistant and light-blocking materi-als, such as coated paper and card-board or plastic bags, to allow forlong-term storage. Prepared foodsare packaged similarly or in glassjars or tin cans, depending on thetype of food. Take-out foods areusually packaged in paper or plastic,

which are lightweight materials andwhich are often made into contain-ers for heating or eating the food.Beverages are usually packaged inglass, aluminum, plastic, or compos-ites. Such materials are watertightand in some cases recyclable. Acceptother generalizations that studentscan support with evidence or logicalreasoning.

3. Suggest that students organize theirdata in a chart. A portion of a sam-ple chart appears below.

4. Students might define overpackagingas packaging not necessary to protector contain contents or provide neces-sary information. Have students giveexamples of any overpackaged foodsthey found and explain how thepackaging could be reduced.

Answers willprobably include the nature of the foodto be packaged, properties and cost ofavailable packaging materials, the needto attract consumers, the need to carrynutritional information, weight ofpackage, ease of manufacturing andshipping, convenience, how the pack-age will be disposed of, and so on.

I WonderHave students work in groups tobrainstorm questions.

Material Advantages DisadvantagesPaper lightweight

biodegradablecan be printed on

tears easilynot waterproof

burns easilyPlastic lightweight

easily made intodifferent shapes

may be microwaveable

may not be recyclablenot biodegradable

Steel strongairtight

watertightopaque

recyclable

not microwaveableheavy


esign ConnectionDD

Some fruits release a hor-mone, ethylene (ethene),that helps them ripen. Askstudents to set up an experi-ment in which two unripetomatoes are placed togetherin a plastic or paper bag andtwo other unripe tomatoesare left unwrapped to ripen.The tomatoes in the bagshould ripen sooner becauseof the ethylene that becomestrapped in the “package.”Have students use theirresults to design packages inwhich tomatoes would ripenas they are being shippedfrom grower to grocer.

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Interpretations of the Data1. Which material was used most often in the packaging

your group examined? Why do you think this material isso widely used in food packaging?

Reflections2. Were you surprised by any of the results? Explain.

13

Putting It All Together1. Choose one of the foods from the data table you made in

Part A and use what you learned in Part B to explainwhy it might be packaged the way it is.

2. What generalizations can you make about the types ofmaterials used to package fresh foods? staples?prepared foods? take-out foods? beverages?

3. What are some of the advantages and disadvantages ofusing each of the following materials in food packaging:paper, plastic, steel, aluminum, glass, and composites?

4. How would you define overpackaging? Would you con-sider any of the foods you examined to be overpackaged?

What factors do you think foodpackaging designers take into account in designingpackages?

I WonderNow that you’ve had a chance to look at some examples offood packaging, what new questions do you have aboutfood packaging materials? Write down at least threequestions and tell how you could find answers to them.

esign ConnectionD

Note on Paper RecyclingPaper that has come into direct contact withfood cannot currently be recycled becausethe food residues interfere with the paperpulping process. Some food-contaminatedpaper, however, can be used as fuel in cer-tain types of furnaces.


This articlecompares theproperties of

paper and cardboard, glass,metals, plastics, and compos-ites used as food packag-ing materials. Note thatMunicipal Solid Waste refersto wastes from residential,commercial, and institution-al (schools, hospitals, etc.)sources.

How to Use These PagesAssign this article for gener-al reading after studentshave completed the activity.You might also divide theclass into five groups, assigneach group a type of mate-rial, and ask groups to readabout their material andcompare the information totheir observations from theactivity. Have students dis-cuss how their own observa-tions confirmed or contra-dicted information in thearticle.

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How do food packagingdesigners make decisionsabout which materials to use?First, they think about thecharacteristics of the food tobe packaged and the type ofprotection it needs. Other con-siderations include how thepackaging will be manufac-tured, used, and disposed of;the cost and availability of dif-ferent packaging materials;information that must appearon the package; and govern-ment packaging regulations.Depending on these designgoals and constraints, adesigner will choose from anumber of basic materials.

Paper and cardboard are twoof the materials most widelyused in food packaging. Paperis made from wood fibers, and

cardboard is made of pressedpaper pulp or pieces of paperglued together. Paper has anumber of properties thatmake it useful in food packag-ing. It is lightweight, relativelyinexpensive, not airtight (goodfor foods that need to“breathe”), andcan be easilyprinted on. It’snot, however,water- or grease-proof, although itcan be coated withwax or plastic to giveit those properties.Paper has someenvironmental advan-tages as well. It comesfrom a renewableresource—trees—and, under theright conditions,

paper is biodegradable. Mostpaper is also recyclable.

Another common foodpackaging material is glass,which is made of sand andother compounds meltedtogether at high temperatures.Among the properties thatmake glass useful for foodpackaging: it’s transparent,airtight, watertight, micro-waveable, and non-toxic. Itcan also be molded into manydifferent shapes. Althoughglass is brittle and can shatterwhen dropped, it makes astrong container, even for con-


On your hunt,you probablyfound foodpackaging

made of paper, glass, steel,aluminum, and plastic, orcomposites of those materials.What properties did youidentify for each material?Compare the informationbelow with your own ideasabout these materials and theiruse in food packaging.

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Glass packaging is often used forbeverages.

Materials Used in Containers and Packaging% by weight in Municipal Solid Waste (MSW), 2003

Glass14%

Plastics16%

Steel4%

Aluminum3% Wood

11%

Paper and cardboard52%

Other<1%

Note on RecyclingRecycling often conserves the use of otherresources as well as the material being recy-cled. For instance, recycling one ton of glasssaves one ton of oil used in manufacturingnew glass. Recycling glass also reduces wateruse by 50%.

Note on Packaging MaterialsAnother wood pulp product commonly usedin food packaging is cellophane. Although itlooks like a plastic film, cellophane is actual-ly made from regenerated cellulose. Thistransparent packaging film is greaseproofand holds its form when twisted or creased.Cellulose packaging is easy to tear and open,can be printed on, and is easily sealed withheat.

Note on Plastics Used in PackagingAccording to recent statistics, the percent-ages of different plastics used in all types ofpackaging are as follows:


Ask student volunteers toresearch the pH of commonfoods and identify examplesof acidic foods and basicfoods for the class. If possi-ble, ask students to demon-strate the effect of an acidicliquid (vinegar, tomato juice,lemon juice) on an uncoatedpiece of metal and on a pieceof glass. After the demon-stration, have the class dis-cuss how the pH of a foodcould affect a packagingdesigner’s choice of material.

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HDPE 29%

PS 11%

PP 10%

PET 9%

PVC 5%other 3%

LDPE 33%


such as carbonated drinks. Inaddition, glass doesn’t reactwith most substances, so it canbe used with acidic foods,such as those containing vine-gar. Because glass melts only atvery high temperatures, it canalso be used for foods that arepackaged while hot. Manyglass containers can be steril-ized and reused as well asrecycled.

Metals used in food packag-ing include steel and alu-minum. “Tin” cans are actuallymade of steel coated with athin layer of tin. The steelmakes the can strong, and thelayer of tin keeps the iron inthe steel from rusting. Properlysealed, tin cans keep out mois-ture and air and preserve foodsfor years without refrigeration.Tin cans can also be recycled.One disadvantage of tin cans,however, is their weight, whichincreases transportation costs.

Aluminum is not as strong assteel, but it is much lighter—about one-third as heavy. Thatmeans that food packaged inaluminum cans weighs lessand costs less to transportthan food packed in tin cans.Aluminum foil is also used infood packaging. Foil is opaqueand thus protects foods from

light. It can also keep outmoisture and air. In addition,foil can withstand high tem-peratures, so it can be used inpackaging designed to be heat-ed in an oven. Since thin foiltears easily, however, it is oftencombined with paper or plas-tic for added strength.

One disadvantage of alu-minum is that it reacts withcertain chemicals. So, forexample, to keep the acids incarbonated drinks from attack-ing the aluminum, beveragecans are coated with a thinlayer of plastic. Aluminum isalso very expensive to produce

because the process requires atremendous amount of energy.Fortunately, though, alu-minum can be recycled. Usingrecycled aluminum reducesthe amount of energy neededto make new aluminum prod-ucts by 95%.

An increasingly popularfood packaging material isplastic. Plastic has many prop-erties that make it useful forfood packaging. It’s light-weight, waterproof, resistant tobreaking, and microwaveable.In addition, plastic can bemade into rigid containers,flexible pouches, or film.

Different plastics have dif-ferent properties. For example,some plastics are strongenough to withstand the highpressure of carbonated drinks.Some hold up under the hightemperatures required forcooking and baking. Othersmelt at low temperatures andcan be used to shrink-wrapfoods.

Plastics have disadvantagesas well. For the most part,plastic containers are notbiodegradable or easily recy-cled, so they quickly end up inlandfills. In addition, plasticsare made from petroleum, anonrenewable resource.

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Aluminum cans are widely recycled.

Enriching Science ExperiencesStudents can investigate the paper recyclingprocess by making paper out of old newspa-pers or other uncoated scrap paper. First,have students tear the newspaper into smallpieces. Add the pieces to a pan of water andheat on medium heat for several minutes,stirring frequently. The mixture shouldresemble oatmeal. Let the mixture cool,then process it in batches in a blender untilpulpy. Mix the pulp with more water in a

large plastic tub. Use a papermaking screen(available at art supply stores) or fine plasticneedlepoint mesh to form the paper. Put thescreen or a large piece of mesh into the tuband lift it up through the pulp. Let it drainfor a minute or two, then flip it over onto aclean sheet of newspaper. Lay another layerof newspaper over the screen or mesh anduse it to blot up the excess liquid. Then care-fully lift the screen or mesh and let the newpaper dry.

are made from petroleum, anonrenewable resource.

Some of the plastics com-monly used in food packagingare listed on the left. You canidentify these by the recyclingcode printed on containersmade of each material.Although all these plasticshave recycling codes, so faronly PET and HDPE are wide-ly recycled.

Along with other materials,packaging designers todayuse composites—packagingmade from several differentmaterials, such as paper,metal, and plastic, bondedtogether. Composites takeadvantage of the differentproperties of the differentmaterials from which they’remade. Juice boxes, for exam-ple, are made from a compos-ite of paper, metal foil, andplastic bonded together. Theyare lightweight and can keepjuice fresh for six monthswithout refrigeration. Onedisadvantage of composites,however, is that they are hardto recycle. Most recyclingprocesses cannot handlemixed materials.


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Plastic RecyclingCode

polyethyleneterephthalate (PET orPETE)

Common Uses

rigid: bottles for carbonateddrinks and juices, oven-ready trays

high-density poly-ethylene (HDPE)

rigid: containers for milkand other dairy products,bottled water

polyvinyl chloride(PVC)

rigid: containers for cooking oil, bottled water

low-densitypolyethylene (LDPE) film: wrapping for baked

goods, candy, dairyfoods, meat, and produce;shopping bags; shrink wrap

polypropylene (PP)

polystyrene (PS) rigid: produce baskets,containers for dairy foods

film: shopping bags,liners for food boxes

film: wrapping for meat,fish, poultry, and other foods

film: wrapping for candies,snacks

rigid: bottles and tubs

foam: clamshell con-tainers for fast foods; hot-drink cups; disposabledishes; egg cartons; meattrays

rigid: squeezable bottles

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Plastic recycling center


Extending ThinkingHave a student read the finalparagraph about compositematerials aloud. Ask theclass to try to explain thespecific purpose of eachmaterial—paper, metal foil,and plastic—used in thejuice box composite. Thenask students to considerquestions such as these:

What materials would youuse if you were designing apackage that needed to beboth waterproof and light-weight? opaque and water-proof? recyclable and resis-tant to acids? microwaveableand lightweight?

Encourage students torecord the kinds of plasticsthey found in the food pack-aging they examined for thisactivity. They can refer tothe recycling codes on thebottoms of the containers oruse the chart on page 16 tohelp them identify differentkinds of plastics. Ask themto calculate the percentage ofdifferent plastics used in thepackaging they examined.

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