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DOCUMENT RESUME

ED 107 513 SE 019 190 .

AUTHOR Boeschen, John;*Amd.OthersTITLE Exploring Your Sense of Smell. Science Study Aid clo.

10.INSTITUTION Agricultural Research Service.(D0A), Washington,

D.C., -PUB DATE Feb 75

NOTE 21p. ..AVAILABLE FROM Superintendent of Documents, U.S. Government Printing

Office, Washington, D.C. 20402 (Stock dO.001A-000-03393, $0.40)

EDRS PRICE MF-$0.76 HC-$1.58 PLUS POSTAGEDESCRIPTORS *Instructiohal Materials; Interdisciplinary Approach;

*Junior High Schools; *Learning Activities; LesOn,' Plans; *Science Education; *Secondary Education;

N Sensory Experience; Teacher Developed MaterialsIDENTIFIERS *Odos

ABSTRACTThis Science )Study Aid (SSA), structured for grade

level 7-9; is based on work 'of the U.S. Department, f Agriculture'sAgricultural Research Service (ARS) conducted at the Western RegionalResearch Center in Berkeley, California. It is, concerned with foodaroma, its intensity and character, and olfactory thresholddeterminations. The SSA provides students with background informationto help understand, the importance of determining odor preferences andol tory.thresholds. There are three investigations for the studenten itled: Fruit Flies and Bananas, Preference Tesing, and OlfactoryThreshold Deterbination. In the section entitled Tp tge Teacher,sucf4.'estions are provided fof each of the investigations to facilitateclassroom use. Included are Materials Lists, Directions forPreparing Solutions, and Suggested Readings and Films. (BT)

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Exploring YourSense of SmellDeveloped by John Boeschen, a secondary science teacher infinale. Calif. Mr. Boeschen prepared the manuscript in co-operation with Dr. John E. Amoore and Mr. Dante G. Guadagni,scientists of the Agricultural Research Service. U.S. Depart-ment of Agriculture,. at the Western Regional Research Center,Berkeley. Calif.

Science Study Aids (SSA's). are designed to supplementyour regular science curriculum,by providing you and yourstudents with up-to-date, research - ,.'elated investigations.

SSA's are designed so that they may be :easily repro-duced for your students. They are public informationnotcopyrightedand may be reproduced without authoriza-tion. However, before using the investigations in yourclassroom, check the procedures to be sure they meetschool safety regulations in your State or county.

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TO THE TEACHER

This Science Study Aid (SSA) isbased 111)4 _work of the "Lt.S. Depart-ment of Agriculture's Agricultural Re-search Service ( ARS) conducted At theWestern Regional Research Center inBerkeley, Calif. It is concerned withfood aroma, its intensity and character,and olfactory threshold determinations(the lowest concentration. of a substancethat can be repeatedly distinguishedfrom water, by its odor). The SSA pro-vides students with background informa-tion to help understand the impOrtanceof determining odor preferences andolfactory thresholds. There are three In-vestigations for the $tudent. In this sec-tion, entitled To the TeacNer, sugges-.tions are provided for each of the In-vestigations to facilitate classroom use.

Exploring Your Sense of Smell isstructured for grade levels 7-9. It is de-signed to stimulate creative thinkingand to act as a focal point for class orgroup discussion. The Investigations at-

quaint students with scientificrprocedpre,and are geared to reinforce basic.mathe-matical concept~. This SSA is an appro-priate supplement to general sciencecourses. Also. it is readily adaptable tovocational education and social science(constimer economics) classes.

.In the sect:on, To the Student, fol-lowing. students are introduced to theconcept of prim-ary odors and "odor-blindness" (anosmia). Here, we haveexplained to students that ARS scientistDr. John E. Amoore first suspected theexistence of what he called primaryodors when he realized that there werepeople who could not smell (were anos-mic to) certaiwodors. As of T974 he sus-pected the existence of '27 such odors.

Because of the increased use of syn-thetic food products such as whippeddesserts, sauce mixes, and instant break-fast drinks, the need to identify theseodors has he ome increasingly impor-tant. Flavorants must be added to make

MATERIALS LASTSFor your convenience. we have listed below the materials needed to perform all the

Investigations contained in this Science Stt dy Aid. T following list gives the quantitiesneeded for each team of four students

STUDENT MATERIALS10 Dro;ophila (fruit flies)1 fermenting banana1 wide-mouthed gallon jar with lid

(or aquarium)2 baby-food sized jifS with lids .

opaque paper (to cove oie small jar)2 narrow-mouthed polyethylene

bottles (250 min with plastic caps2 plastic strawsodorous food substances (water

soluble) for test solutions.2 to 3% TSP (trisodium phosphate)

solutionvacant table or desk to be used as

an Odor Research Bar for testing

TEACHER MATERIALS;east

OPTIONM.

putrescine (see page 4)

buffer solution of borax (sodium tetraborate10H.0)

distilled waterSt,nsen burner

containers for soldtions

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bland synthetic foods more palatable.°Correct identification and chemical anal-ysis of the-primary 'odors help ARS re-searchers in their efforts to discos.: er ef-fective and safe (non- toxic) chemicalsfor flavoring.

As suggested in the section To theStudent, a solution of the primary odor1-pyrroline can be prepared to help sep-arate the nonsmellers from the smellersin your class. In this country, 17 percentof the population is anosmic to this

' chemical. Your students may find it in-teresting to discover what percentage oftheir class is "odor-blind" to 1-pyrroline.We- have not included this test in thefollowing inVestigations, but have pre-sented the "recipe" below in case yourstudents wish to investiga,te.

PREPARING 1-PYRROLINE

1-Pyrroline is not available 'commer-cially. However, its odor usually is pres-ent in putrescine as an impurity.

1. Prepare a buffer solution of borax(sodium tetraborateNa2B467.10H20).Place 38 grams of the chemical in 1liter of distilled water. Warm the putres-cine to at least 27°C to melt it. Thenadd 1,4 cc of the melted putrescine to500 ml of the buffer soltition.

2. Put-the putrescine solution in one"bottle and an equal amount of the buffersolution in another. Ask students toidentify the bottle with the odor (seeFigure 2).

Putrescine can be obtained from theAldrich Chemical Company at the fol-lowing addresses:

10 Ridgedale AvenueP.O. Box AACedar Knolls, N. J. 07927

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90 West Saint Paul AvenueMilwaukee, Wisc. 532332098 Pike Street aP.O. Box 1814San Leandro, Calif. 94577

RAISING FRUIT FLIESFOR INVESTIGATION 1

Drosophila neelanogaster (fruit flies)are attracted by, and found in abun-dance in soft, aromatic fruits such asgrapes, bananas, and plums, especiallyif they are overripe and have begun totferment. Adult flies as well as theirlarvae feed on fruit juices: and sinceyeast is ,present wherever fermentationis in progress, it is believed that yeastconstitutes an important part of theDrosophila diet. Consequently, Droso-phila may he raised on any fermentingmedium.

A simple method to develop a colony.of Drosophila is to dip a piece of well-ripened banana (peeled), 1.1/4 to 21/)inches long, into a 2 to 3 percent susension of yeast in water. Then .put thbanana in a small glass container suchas a shell vial, one-pint milk bottle, or asmall mayonnaise. jar. Narrow-mouthcontainers hold-the banana food in placebetter than wide bottles.

Place thjar in'a warm locationthewindow sill in your kitchen, outside neartrash. containers, or in your school'skitchen area. In 2 to 7 days the Droso-phila colony should reach a populationsufficient for the Investigation: Trap theflies in the container by closing it.witha cotton plug or other suitable coveruntil you are ready to use them. Fliesthrive for several weeks in cultures pre-pared in this way, provided good-cultureconditions are maintained.

In the .Investigation the students will

be doing, the Drosophila are drawn' tothe fermenting banana hecause of itsodor. The senses of sight, sound, andtouch play no significant role in attract-ing them. Be 'sure the banana does notcome in contact with the outside of thesmall jar or with the inside of the gallonjar (see Figure 1). Such Acontaminationmay lead the flies away from the orig-'inal banana. Place the banana inside'thelarge jar just prior ,to releasing thefruit flies:

SETTING UP ANODOR RESEARCH BAR FORINVESTIGATIONS 2 AND 3

These Investigations require that theclass be divided into research teams. Thearea in which. each team performs itsInvestigation is called an Odor ResearchBar. In setting up the Odor ResearchBars, itteition should be paid for teamstructure. We would suggest that eachresearch eam consist of four members.--Wherithe lassisconducting its prefer-ence tests, team-member jobs might beoutlined as shown following, You maywish to duplicate or copy these studentjobs and activities and pass them out tothe team meniaerS, or place them on ahandy bulletin board for the'entire class.-

In both Investigations 2 and 3, thecontents of the bottles should be revealedonly After each Investigation has beencompleted. ` r`

Teem Jobs for Investigation 2PrefIrence Testing

Job 1. One team member signs andhands out the questionnaire.

Job 2. A second team member admin-.isters the test to see that it isdone correctly.

Job 3. The third team member col-..

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lects the questionnaire andtranscribes 'the data, on the

'team's data sheet.

Job 4. The fourth team member teststhe samples at his and theother Odor Research Bars.

When the fourth member feturns tohis Bar;:he assumes Job 1, and everyoneelse perform_ s the next job in line. Thelast person on the team now starts hispreference testing. The actual testing is

-over when all members of all teams havecompleted their choices.

Team Jobs for Investigation 3Olfadtory Determination

In measuring olfactory thresholds, thejob assignments essentially are the samewith minor deviations :

Job 1. This team member signs hisname to the questionnairebrought to him by the studentjudge.

Job 2. Once again, one member seesthat the test is administeredproperly.

Job 3. The third member checks tosee that the form has beenfilled out correctly, and makescertain the student judge waitsat least°30 to 60 seconds beforegoing on to the next Bar.

Job 4. The fourth, member of theteam, the student judge, goesto all the Odor Research Barsand tests the samples foundthere.

When the fourth member returns fromtestify, he assumes Job 1 and everyoneassumes and performs the nexLjob inline:

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.PREPARATION FORINVESTIGATION 2

Food Acceptability and Odors

Discussion of the results from Investi-gation 1 eventually will lead students tothe question, "Are odors also importantto man?" Reasons, pro and con, can belisted on the blackboard and in studentnotebooks. If yonateel the class needsan extra push to get them going, cut aslice of apple and rub a small amountof almond extract on it (any essencewill do, as long as it doesn't discolor theapple slice.- .Other possibilities includeorange_extract, dilute vanilla extract, ormint saucecheck the spice section ofyour local supermarket).

Next, ask one of your students of he'deat it. There'll be some hesitition andeventually a remark to the effect, "Itdoesn't smell right." Ask the students iftheir parents would buy s bag of applesthat smelledthat way. This highlights amajor problem that concerns, food prdc-,essors : Food must smell the .w.y thepublic expects it t6' smell.

The Odor'Research Bar as Testing Pane!One of the methods used to irisure'the

quality of aroma is the testing panel.This is a group of people who aid foodprocessors and researchers in evaluat-ing odor according to such factors aspreference and intensity. Their equip-mentthe human nose. This SSA makesuse of such panels and allows the Atu-dents to determine their own prefer-ences among certain foodstuffs.

In trial runs of Exploring Your Senseof Smell, comparisons of canned orangejuice/frozen orange juice, grape soda,'grape juice, and "organic" apple juice,'regular apple juice were made. Thenutnber of odorous substance's availableto use are almost limitlessTabasco

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sauce, soy sauce, garlic, sauerkraut' juice, fish odors such as cod liver oil

and clam juice, curry and other spicesand herbs, perfumes, mint sauce, hoMe-radish,- peanut butter, ini7k so on ! Forac.urate results, the tests should be runat least two or three times. You shouldalways have the samples prepared be-fore class time. If your class tests an-other class, the teams may prepare thesamples at their Odor Research Bar.

Using the Forms and Charts

Notice that all the forms are designedfor foiir Odor Research Bars. Bothblank and examples of completed formsare provided at the end of each Investi-gation.

Questionnaire Form: On the bottomhalf of the form are two squares withlines beside them. Before the sheet ishanded to the student judge, the num-bers of the two samples being tested areto be written on the lints by the mem-ber of the team performing Job 1. Thejudge, in turn, is to rlace a check markin the square next to the number of thesample he preferred.

Team Data Chart: The sample num-bers ale to be put in the boxes on theleft side of the chart. When ti judgefinishes making his preference selec-tions, he.hands his sheet to the recorder(Job 3) of that particular Bar. The re-corder then marks down the judge'spreference on the team data sheet bynutting a "B" foe every boy vote or a"G" for every girl vote in one of thesmall boxes next to the preferred sam-ple. After all testing for 1 day is com-pleted, the tallies for bays and girls arctotaled individually and then together.This final tally- number is entered in therectangular box after "Boy" or "Girl"totals. Using these data; the class fills

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out the Class Data Chart together.The, Class Data Cluert: This chart is

to display all the data collected, and toreinforce addition, division, and -per-cents (or fractions). The. ,ertical col7umnsslabeled "Girl Prefer races," 'totalGirl and "/0 Girl Prefer-ences" should be treated as .one, unit.The same is true for the three "Boy"columns. The sum of the two numbersentered under "Girl Preferences" equalsthe number 'of "Total Girl Judgments."The formula looks like. this:

Girl Preferencesx 100 = % Girl Preferences

Total Girl Judgments

The same procedure is used in fabulat-°ing the calculations for "Combined Boy .and Girl Preferences per Product," "134and Girl Total Judgments," and "TotalPreferences."

PREPARATION FORINVESTIGATION 3 °

Olfactory) threshold is the term usedto describe the weakest solution of anodorous substance that can be repeat-edly distinguished from plain water.This Investigation is designed to deter-

the average olfactbry threshold ofthe class for' a substance of your &ice.The samplei used in this Investigationshould be those familifir to the students.In gne trial class, the students ilecer-mined their average olfactory thresholdfor horseradish. The possibilities ofchoice are alai st unlimited.

'Preparing the Nutions1. Ponr 100 ml of the undiluted sam-

ple into a testing bottle. The con-centration of this sample Pill bearbitrarily defined as Concentra-tion J. .

2. Pour 100 ml of fresh water into a

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beaker. To it add 100 ml of' theundiluted sample and stir well. 'Pour 100 ml of this dilutea solu-tion into a test bottle. The con-centration of this bottle will be 1,4of the first bottle, or 0.5. Savethe remaining 10p ml of solutionfor Step 3.

3. Add 100 ml of water to the 100 mlof solution remaining from Step 2and stir well. Pour 100 ml of thissolution into one of the poly--ethylerie test bottles. The concen-tration of this solution is 1/, thesecond bottle, or 0.25. Save theremaining 100.ml of solution forStep 4.

4. To the 100 ml of solution remain-ing from Step 3, add 100. ml offresh water and stir *ell. Pour100 ml of this solution into a testbottle. Thd concentration of thisbottle is 0.125. Save the-remain-ing 100 ml if you wish to makefurther dilutions. If so, proceedas in Step 3 above.

The odor of the last concentration youprepare should be barely detectable, ifat all. Your nose .will have to be yourguide. If you feel all the concentrationsare too strong, start over and usa'a moredilute starting solution, calling it Cori-centration 1.- Halving the other samplesin the manner described above will giveyou the pro,per serial dilutions.

Each concentration is then placed onan Odor Research Bar where it is pairedwith a bottle containing only water. Theolfactory threshold test should be run atleast twice for best results. When every-one has completed sniffing, fill out theclasS data forms and plot the graphstogether.

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USING THE FORMS, CHARTS,AND GRAPH

Notice that both blank and completedexample forms have, been provided atthe end of each Investigation.

Que tonnaire Charts for Investiga-tion 2. The student judge will.-take the_same questionnaire with him to all theOdor Research Bars. The first memberof each team recrds his Bar numberon the sheet when the judge arrives.At the same time, the numbers of thetwo sample bottles are placed on thequestionnaire. After testing the sam-ples, the judge circles the orie he believescontains the odor. The recorder (Job 3)checks the sheet for accuracy, then signshis name. After all testing has beencompleted, the teacher announces the-concentration of the sample found ateach Odor Research Bar and this is re-corded on the questionnaire. Followingthis, the samples containing the solutionare revealed by the teacher and the'sheets are scored.

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Team Data Charts and Class Graphfor Investigation 3: When each teamhas tallied the number of its correct re-sponses on the questionnaire chart, theteam data chart is filled out 'and theclass graph plotted, using the resultsof all team data charts. Each studentshould be provided with one team chartand one class graph. The intersectionof your 'class curve with the dotted lineon the graph will give you the class aver-age olfactory threshold for the sampletested.

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SUGGESTED READING

Molecidar Bcisis of Odor, Amoore, John E.,Charles C. Thonias (Publish6r), .BaifnPr-stone House, Springfield, Ill., 1970.This is a Very technical book and is rec-ominend'ed for teachqrs who wish Id gointo grepter'detairon the stereochemicaltheory. of odor. '

"The' Stereochemical Theory of Odor,"Amoore, John. E., Johnston, James W.,Jr., and Rubjn, Martin; Scientific Ameri-can, February 1964. Available in mostlibraries. This article deals.' primarilywith the stereochemical theory of odor.It is easy reading and recommended foradvanced classes.

arolina Drosophila Manual, Flagg, Ray,mond 0., Carolina Biological Supply Co.,,Burlington, N.C., Gladstone, Oreg., 1973.Detailed information on rearing fruit..flies.

"Specific Anosmia: A Clue to'the OlfactoryCode," Amoore, John E., Nature, (Lon-don), Vol. 214, pp. 1095 to 1098 (Jane 10;1967). This article is recommended forteachers who are interested in detailedinformation relating to anosmia and pri-mary odors. It is not recommended forstudent reading.

Drosophilia Guide: Intro* duction to theGenetics and Cytology of DrosophilaMelanogaster, Demerec, `M., and Kauf-mann, B. P., 8th ed., Carnegie Institu-tibn of Washington, Washington,, D.C.,1972. An in-depth guide to raising fruitflies with `step -by -step, instructions. Rec-ommended for teacher use only.

SUGGESTED FILMS"Sehse Of Smell," Science in Action broad-

cast, 1965. Write to TV Dept., CaliforniaAcademy of Sciences, Golden Gate Park,San Francisco, Calif. 94118. 16 mm color.Excellent film covering stereochemicaltheory, primary odors, importance toman, 'and' testing procedures. Recom-mended for all classes. ,

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TO THE STUDENT

You probably hear tilt word "flavor"many times a day:the creamy flavor ofa chocolate milkshake, the nuttyflavorof the peanut butter and jelly. Sandwicliyou had for lunar, or.perhaps the "wide-awake" flavor of your morning orangejuice.. A number of thing- influenceflavortaste, odor, color; texture, evenyour mood. One of ,.he most importantof these is odor. An °apple that looksgood but doesn't srriell the way you thinkan apple Should smell probably won'thave a good apple flavor.

To discover how important odaris indetermining the flavor of food, do thefollowing mini - investigation : Have. afriend blindfold you. Then, holding yournose, eat a small slice (apple andPthena small slice of rad'sh. Could you tellthe difference bet een the two foods?Was it a big diffe ence? Because odor isimportant in determining, the flavor ofa food, food packageri and grocery storemanagers are carefhl to insure thattheir,products smell the way people ex-pect them to smell. -. Animals, such as your dog or cat, use

gieir sense of smell as a warning.device.WiTren a dog or cat leaves his territory,his .sense of smell warns him both ofseen and unseen dangers. Unlike ourpets, we don't rely on our sense of smellas heavily, but there may be times whenour safety depends on out ability tosmell. For exaMple, if you open. a canof fish or meat that has spoiled, a putridodor may reach your nose early enoughto warn you of possible danger to yourhealth.

Many homes in Mir country are heatedby gas. Did you know that refined gasis odorless? Because of this, gas com-panies add, special chemicals, calledodorants, to the gas so that it can be

'easily detected were a' leak *to Occur.However, people differ in the intensity

of the odors they can perceive. In fact,just as there are people who are color-blind, there are people who are `odor-blind" (anosmic) to certain smells.

Suppose that an odorght to which 10out of every 100 people are anosmic isadded to a city's., gas supply as a safe-

, guard: If a gas leak were to occur, whatmight happen to those people who couldnot detect the odor of the gas? Researchinto our sense of smell has insured thatodors detectabile by tbagreatest percent-

instances sutkas the one just described .age of the population are used and that

Dr. John E. Amoore, Research Chin-do not occur. /ist with the Agricultural Research Ser-, 1.ice (AIRS) of the U.S. Department ofAgricultur at the Western Regional Rsearch Cen er'in Berkeley, .Calif., is w 1known for his piondexini research i tothe sense smell. At his laborato inBerkeley, r. Amoore is investr tingsame of th complex factors reap a nsiblefor the fla or of food. He belie esthatthere are primary odors just as thereare priniary .colors. Ine1969 e.hypoth-esized the existence of 27 o these' pri-inary odors.

According. to Dr. Amoore, primaryodors are similar to the Primary colorsin that all odors can be made from dif-ferent combinations of these 27 imary ,

odors. By. 1974, he had experimentallydetermined two of the primary odors :the sweat odor of the chemical isovalericacid and the cornlike odor of i-pyrroline.

In this country, 17 percent of the pop-ulation is anosinic to 1-pyrroline. Youmay wish to ask, your teather to pre-pare a sblution of the primary1-pyrroline, which will enable you toseparate-the "odor-bliltd" fromthe "non-odor-blind" students in your class. Youcan then calculate What- percentage ofyour class is anosmic and compare it

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FIGURE 1

with the national average of 17 percent.

Our scientifically orientefl world todayuses comrilicated 'techniques subh as gaschromatography to separate and identifythe different partg of chemical matures,.and Infra-red and ultra-viiolet absorptionspectroscopy. to identif.y chemicals bythe amount of infrA-rediand ultra-violetlight they absorb.' However, despite ouradvanced technology, seienti* must de-pend most heavily on the hUlnan noseto help identify-the odors,of differentchemicals. Oddly, people are more accu-rate than scientific equipment in thiskind of research. This is why ARS sci-entists use testing panelsgroups ofpeople and Weir noses to aid item intheir research investigations.

In the, following 'Investigations., youand you.r..classmates will set up testingpanels similr to the ones used by ARSscientists. You will then be able to per-form research showing which odors are

_both preferred and most easily detectedby people.,

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INVESTIGATION 1.Fruit Flies and (bananas

Materials ,(per team)10 Drosophila1 fermenting banana (peeled)1 wide-mouthed gallon jar with lid or

aquarium2 small jars (baby-food size) with lids ,

opaque paper (enough to cover -one of thesmall jars)

PROCEDURE1. place. the fermenting banana in a

small, uncoiered jar. Put this jar in-side and at the 'far end of the galloncontainer laid on its side or in anaquarium (see 'Figure 1).

-NI 2. Place the small coveted jar contain-ing the fruit fly culture just insidethe opening of the gallon jar. Then .

remove its covering. Next, quicklycover the gallon jar /so that the- fruitflies cannot escape.

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POLYETHYLENEBOTTLE

SAMPLESOLUTION

FIGURE. 2

3. Observe the fruit flies. Describe theirbehavior in your notebook:

Questions for Thought1. Once the-fruit flies are released in-

side the larger container, ,mhat dothey dor

2. Which of the following senses dothe Truft flies use to arrive at theirdestination?

sight' sound,

smelltouch

, 3. Can you devise an investigation us-ing the opaque paper to dis,.:over iffruit flies can locate the bananawithout seeing it?

Extending the InvestigationSet. up your own investigation to ills-cover if fruit flies are' attracted toother things..Go back fo your original investigation

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and see if you can find other orga-nisms that bfinanas attract. '

Suggested ReaflingThe Science of Smelt, Wright, R. 11., George

Allen & Unwin Ltd., LOndon, 104. Amajor portion of this work is devoted toanimals and smells. Chapters 3 and 4deal specifiCally with fruit: flies Veryeasy reading. ,

INVESTIGAT1164,2,Preference Testing

\ Materials (per team),

'2 narrow mouth polyethylene bottles (250.\ ml) wish plastic caps2 plastic straws .12 sample solutions to be tested/per Bar2 to 3% TSP jtrisodium phosphate) solutionquestiorinaires (a quantity equal to the total

number of students taking the test perBar)

1 group data sheet

PROCEDURE1. Wash the bottles, in the 2 to ,370

TSP (trisodium phOsithate) solu-tion provided by yotir teacher andthen thoroughly rinse, with waterto be sure the bottles are odor-free.

2. Drill a hole the size of the strawsin the bottle cap. Irsert plaaticstraw into each of the hales justdrilled into the caps (the \ItrawsShould fit snugly Into the hope).Pour equll amounts of the samplesolutiotirprepared by your teacherinto the clean test bottles.Fasten the straw/ cap unit 'tightlyon the bottle. Be sure -.that the encl.kof the straw is well above the solu-tion so that the sample will not be

3.

4.

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FIGURE 3

squirted when the bottle is squeezed(see Figure 2). .

5. If the solutions can be seen throughthe bottle, cover the outside withopaque paper.

6. Your teacher will w cod(; the bot-tles for you with r omly selectednumbers.

7. After the bottles are placed on theOdor Rksearch Bar (see Figure 3),each student judge should thengently squeeze the polyethylene bat-tle so that a puff of air enters hisnose. He may take as long to, sniffas he wishes.

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8. After he has made a choice as towhich sample he prefers, he shouldwait 30 to 60 seconds, then pro,ceed to the next-Bar.

9. After all samples have been tested,each team must clean up its area.Be sure the sample bottles arewashed with TSP and rinsed thor-oughly with water.

10. When the preference test has beenrun for- the final time, fill out theClass Data Chart together.

Questions for Thought1. Which sample in each pair of sam-

ples was preferred?. Why do youthink it was preferred?

2. How do the boys compare with thegirls in their preferences?

3. If you owned a grocery store, whatmight be some of the things youcould learn from this Investigation?

Extending the investigationMake a trip to your local grocerystore to see if they stock more of thetypes of items your class preferred.Tell the store manager the results of-your investigations.Determine your family's preferences .

Determine the preferences of a lower-grade class, then of an upper-gradeclass and compare the results. Arethere any major differences betweenage groups?

Suggested ReadingOdou'r Preferences, Motrtrieff, R. W. Leon-' and Hill, London, 1966. This book is de-vdted to odor preferences, analyzing themaccording to age, sex, and temperament.Ghaptei 19 (pp. 271-96) is devoted toodOrs and'foods. .Good background read-ing.

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QUESTIONNAIRE FORM

RECORDER

JUDGE

Put a check in the box next to the number.of the aroma you like best.

AROMA NUMBER

AROMA NUMBER

ODOR RESEARCH aBAR NUMBER

investigation 2

TEAM DATA CHART

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ODOR RESEARCHBAR NUMBER

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SAMPLENUMBER

PREFERENCE_

TOTALBOYS

TOTALGIRLS

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Investigation 2

CLASS DATA CHART

s-GIRLPREFERENCES

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TOTAL GIRLJUDGMENTS t

PERCENT GIRLPREFERENCES

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BOYPREFERENCES

TOTAL BOYJUDGMENTS

PERCENT BOYPREFERENCES

COMBINED BOY ANDGIRL PREFERENCESPER PRODUCT

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SSA/10

'INVESTIGATION 3Olfactory ThresholdDetermination

Materials (per team)2 narrow-mouth bottles (polyethylene) (250

ml) with lids2 plastic straws1 test solution, provided.by the teacher

' 2 to 3% TSP solutionquestionnaires (a quantity equal to the total

number of students taking the test),1 team data shegt1.; class data sheet per team member1 graph per team-member

4. t;PROCEDURE

You will use the same kind of bottle'sand Odor Research Bar ds you did ininvestigation 2. If necessary, ref& toFigures 2 and 3 in that Investigation.1. Wash -the bottles with the 2 to 3%,

TSP solution provided by your. teacher, then thoroughly rinse them

with water.2. Place the sample solution preimred

by your teacher in one of your team'stwo bottless. Now pat an equalamount of tap water _in the otherbottle. Your teacher will code thebottles for you.

f 3. Place the cap with the straw on thebottle. Be sure the end of .the strawis well above the so1Utio-ti.

4. Begin testing now. Do the testing thesame-way you did in Investigation 2.

,T5. When you have finished _the tests,

clean your team's research area. Atthe same time, go over the data you

6

4

have 'collected to make sure it iscorrect.

6. When you have completed the finalday of testing, fill out the datachartsand plot your graph toggther withthe other Odor Research Bars..

Questions fc5r Thought1. What is the class olfactory threshold

for the substance tested?2. If a perfume manufacturer allowed

an aroma to become too Strong (wellabove the olfactory threshold of hiscustomers), what Might be the re-action of the people who used theproduct? What if the olfactorythreshold was.well below that of hiscustomers?

3. If a gas company put an odorous in-dicator in a gas heating system, but,in anramount below a community'solfactory 'threshold, what do youthink might happen? How could thissituation be corrected? -

Extending the InvestigationDetermine a lower grade's thresholdfor the substance you tested, thendetermine your parents' and teachers'threshold for the same substance.Compare them. Who has the higherthreshold? Who will be most able todetect the presence of the, substancein lowest quantity.3;,.Is there a store in your area thatuses this substance in the preparationof its products? Do you think theamount of substance is above, below,or just at the right olfactory thres-hold for its customers? Do you thinkthis information might be helpful tothe store manager?

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CONCENTRATIONS

1

al@np6Sch@rWAt]

, are a series of free supplementary inve3tigative materials foruse in secondary science classes, grades 7-12. The materials are based on researchof the U.S. Department of Agriculture's Agricultural Research Service (ARS). Theyare written by secondary science teachers working with ARS scientists at researchfacilities throughout the country. Before being published, they are tested in thelaboratory and in classrooms of cooperating teachers.

Several times during the year, SSA's from this on-going Series are sent to scienceteachers, grades 7-12, one copy for ea,-..h teacher. Science supervisors also receivecopies at the same time. Because we .nnot provide enough copies for students,we have designed SSA's so that tear± can easily reproduce the student portionfor their classes.

We hope that you findihe_Science Study 'Aid Series a valuable suppleMent to yourscience curriculum. We welcome your comments on the SSA's that you receive,

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L.

SCIENCE STUDY AIDSINFORMATION DIVISIONAGRICULTURAL RESEARCH SERVICE, USDAWASHINGTON, D.C. 20250

Manufac,urers namos used in SSA s are sulely fur the puluoso of prov.dIng specrlic, iniormation Monhon of a manufacturer sname does nut constitute a guarantee or warranty of the product by the U S. Department of Agriculture or endorsement bythe Department over other manufacturers not mentioned

Issued February 1975

* U S GOVERNMENT PRINTING OFFICE 19750-567-997

For sale by the SupeHntendent of Documents, U.S. Government Printina OfficeWashington, D.C. 20402 Pnce 40 eenta

Stock Number 001-000-03,393