a plan for laboratory activities in general science

A PLAN FOR LABORATORY ACTIVITIES ,

IN GENERAL SCIENCE*IRA C. DAVIS

University of Wisconsin, Madison^ Wisconsin

Many teachers fail to make the best possible uses of the labo-ratory in general science. Too much emphasis is placed on thestudy of the facts and principles given in textbooks withoutbringing these facts and principles within the experiences of boysand girls. Science deals with methods, materials, processes, skills,techniques, observations and experiences. It also provides out-lets and opportunities for the original and creative abilities ofpupils through laboratory teaching.There are five types of laboratory activities which need to be

planned for pupils. These are not to be compared with, or to beconsidered as like the formal laboratory procedures so often usedin science classes. In the first type, emphasis is placed on thegetting of information through the activities planned by theteacher. This type includes skills, techniques, methods and ob-servations as well as the learning of facts and principles. It alsoprovides for originality and creative ability through the follow-up activities suggested.In the second type of activity, pupils are given ^things to do."

Results occur. Pupils raise questions about the results and aproblem is developed. The solution for the problem is developedby the pupils as a group. This is the way problems are discoveredoutside of school.The controlled experiment is the third type of laboratory ac-

tivity. In this type pupils leam the meaning of controls andvariables. They also learn how to plan a controlled experimentand then perform the activities as planned. The controlled ex-periment is one of the greatest contributions science has madeto clear thinking. Pupils should learn how to experiment in thistype of activity.In the fourth type of laboratory activity, emphasis is placed

on the need of verification of things presented in textbooks orthings read in newspapers or magazines. The problem here is toreduce to laboratory procedures the types of activities whichpupils need to encourage them to believe what they have reador heard.

* Read before the General Science Section of the Central Association of Science and MathematicsTeachers at Detroit, November 29, 1946.

146

LABORATORY ACTIVITIES IN GENERAL SCIENCE 147

The fifth type of laboratory activity is built around problemsand projects. Here pupils usually plan the procedures for solvinga problem such as the construction of some new piece of appa-ratus, the laboratory study of some local problem, or developinga plan for the demonstration of some scientific or commercialprocess. Here the emphasis is on doing things and making thingsand giving pupils opportunities for originality and creativeability. It also gives them valuable experiences in using toolsand materials.

If we were to train a person to become a good musician wewould expect him to become skilled in playing some instrument.It would not be enough to study music from a book or learnhow to read music. These are necessary but they do not makea good musician. The same thing is true with training a personto become a mechanic. Certainly we would expect him to knowhow to use tools and machines. Why do we think we can makeboys and girls good scientists without having them learn how touse the great tools and inventions our scientists have made andwithout learning how these great inventions were made possible?Teachers are justified in asking how can these types of labo-

ratory activities be provided under the present conditions in ourschools. True, many schools are not equipped to provide theseactivities, but there is no reason why they cannot be equippedto do so. Certainly it does not cost more to equip a good sciencelaboratory than it does a good home economics room, an indus-trial arts room, a musical organization using musical instru-ments, an art room or a gymnasium. Further, the cost of suppliesneed not be greater than any of the subject areas just mentioned.Financial considerations then are not the cause of poorlyequipped laboratories. We do not have them because teachershave not demanded them and because it is easier to teach sciencewithout them.What is needed for a good laboratory for general science? First

of all, we need good laboratory tables, a demonstration desk,storage cases, running water and two or three sinks. The tablesshould be equipped with gas and some supply of electricalenergy, preferably 110 to 120 volt A.C; current. The demonstra-tion desk should be supplied with running water, gas and elec-tricity. The room should have dark curtains so all forms of visualaids can be used. A work bench is also very desirable.The apparatus and materials should be selected on the basis

of need and frequency of use. The cost is not excessive.

148 SCHOOL SCIENCE AND MATHEMATICS

No doubt you are now asking what kind of activities are to beperformed in .the laboratory. The most fruitful and valuablesource for these activities is to make a list of the workFs mostimportant and elemental inventive discoveries. If you wereasked to select forty of these great inventive discoveries, whatforty would you select? There is not anything sacred about say-ing forty but if you could list forty you would have all of theactivities you could use. I will list forty. They are not necessarilygiven in historical sequence or in the order of relative impor-tance, but they all play a very important part in our everydayliving. Here is the list:

’ MirrorPlants grow from seedsFire and its controlPottery ware, cooking utensilsOil lamps�burning fuels to produce lightBalance�weighingRuler�measurementBow and arrow�sling shotPendulum�keeping time�clocksPlants get raw materials for growth from the air and soil. PhotosynthesisWriting and printing�preservation and dissemination of knowledge. Al-phabet

Lever�pulley, wheel and axleL i

Inclined plane�wedge�screwj ,LensCompass�exploration�magnetismWheel�circular motion�transportationBoat�wate?r transportationPlow�tools for cultivating the soilSteam engine�industrial ageMicroscope�MagnificationsTelescope�Astronomy�optical instrumentsPrism�colorStove�hteating and shelterAir pump�bicycle pumpBarometer�weather predictionsThermometer�heat measurementBlast furnace�blast lamp�blow-pipe, manufacture of iron and^steelMusical instruments, sounds can be produced by setting matter in vibra-

tion.

So far I have listed about 25 great inventive discoveries. Weusually think of the 19th and 20th centuries as being the periodin which most of our inventions have been made, but all of thesewere discovered before this period, many of them more thantwo thousand years ago. Many of our scientific discoveries arevery old.Now to proceed with the more recent discoveries.

LABORATORY .ACTIVITIES IN GENERAL SCIENCE 149

Chemical cell�storage cell�using chemical action to produce an elec-tric current

Electromagnet�rapid communicationElectroplating�electrochemical industriesDynamo�electrical energyElectric motor�use of electrical energy for motionGerm theory of disease�bacteria�yeasts�moldsCell structure of living thingsCanning of foods�food preservationTelegraph�CommunicationTelephone, radio�rapid communicationBunsen burner�mixing air with a fuel before it is burnedPhotography�pictures can be made by chemical action�cameraInternal combustion enginePhonograph�reproduction and preservation of soundsIncandescent light�fluorescent lighting, arc lightVacuum tube�uses in radio, telegraphy, etc.Photoelectric cell, televisionAtomic fission.

This completes my list of forty-five great inventive discov-eries. An inventive discovery is a type of discovery which canbe made the basis of laboratory activity in which pupils learnhow to use these great discoveries and also learn to appreciatetheir importance in our daily living. Possibly five of these dis-coveries could not easily be reduced to laboratory study at thejunior high school level. This leaves forty great inventive dis-coveries that could be reduced to a laboratory procedure at thislevel. All of them have many social implications which need tobe emphasized. Some of you may say I have omitted many dis-coveries of a biological nature such as all living things come fromliving things; Mendelian traits of inheritance, nutritional valueof foods, or the life cycle of insects. They are all very importantbut they are not easily reduced to valuable laboratory activitiesand can better be taught in some other subject areas. Further,many of them require a much longer period of laboratory activ-ity than do the activities in physical science with a consequentloss in continuous interest.Laboratory activities can be performed by pupils of varying

abilities. Investigations appear to prove that poor students areas good observers as good students�both groups have equallygood eyes. Many teachers confuse results with reasons for theresults. Laboratory activities and demonstrations give resultsbut never the reason for the results. Why things happen areexplained by reasoning. The best students do the best reasoning,but it is not necessary for all pupils to know the why of every-thing. We do not know how light passes through glass but that


does not stop us from using glass. Would you think of denyingpupils the opportunity of using a microscope or telescope be-cause they could not explain how the images were formed? Ifyou insisted on that, then more than one-half of our teacherswould never be permitted to use a microscope or telescope. Asanother illustration, I might place equal volumes of water intwo different sized containers and discover that the water evapo-rated more rapidly from the large container. But that does nottell me why it evaporated more rapidly from the large con-tainer. To explain that thoroughly, a pupil would need to knowsomething about molecules, the molecular theory, the kinetictheory, humidity, air currents, temperature and energy changes.How long has it taken the human race to learn that evaporationcould be used as a cooling process for refrigeration? But we ex-pect pupils to learn the same thing from one simple experiment.

I am not attempting to minimize the desirability of havingpupils acquire thorough understanding, but I do want to makeit clear that while laboratory activities and demonstrations dogive us answers for things that happen, they never give us thereasons for these answers. Further, we ought to make it clear topupils that if we use theories to explain why some things happenas they do, it is an admission on our part we may not have thecomplete reason for the answer.For further explanation of what I mean by laboratory activi-

ties, I will give illustrations of two types of activities not usuallyprovided for in our present methods of teaching. The first typeof activity is what I prefer to call a problem discovery activity.In this activity pupils are ugiven things to do91 before any classdiscussion has taken place. In this activity pupils will be askedto attach a candle to a cardboard four inches square by usingthe dripping wax from the lighted candle. Here a lesson in safetyin using a flame may be demonstrated. Each pupil now holdsthe candle flame near (a) beaker filled with water, (b) piece ofplate glass, (c) at different distances from the glass in the win-dow, (d) plastered wall, (e) blackboard, (f) mirror, (g) trans-lucent glass�glass rough on one side and smooth on the other.

Pupils will be encouraged to make as complete observationsas possible and record briefly the observations made.A discussion of results occurs and a problem is raised. What

question do you think the pupils will ask? Why was an image(picture) of the flame formed with some surfaces and not theothers? Here it may be suggested that pupils feel the different


surfaces and observe similarities and differences. They will ob-serve some surfaces are smooth and others are rough, some aredark and others are light colored. Some are transparent, othersare opaque. They may even say some are translucent. They willnow conclude that all of the smooth surfaces formed imageswhile the rough surfaces did not.Now to test their ability to apply results. Direct the pupils to

stand in front of the different surfaces where they can see them-selves. If this is not possible, ask them to place the candle nearthe surface in the room where the most distinct image will beformed. There should be some such surface in the room whichhas not been used.

This is not the end of the problem, it is just the beginning.Now pupils want to learn something about the image. In plan-ning the following activities the teacher wants them to learnthat the image is erect, it is reversed, and the image appears tobe behind the reflecting surface. Some pupils may have observedthese characteristics of the image. Next the pupils will hold thecandles near a window pane, and bring pencils toward thecandles from the right. Then move the candles back and forth infront of the glass, then above a beaker of water at one side whilethey look into the water from the opposite side.

It is not easy for pupils to understand what is meant when wesay the image is reversed (backwards). Next have them hold amirror in front of their eyes with one hand and place a finger ofthe other hand on the eye that appears on the left in the mirror.Then have them write their names on sheets of paper and holdthem parallel with the mirror and observe that they see in themirror. Then have them write their names so they appear to becorrectly written as observed in the mirror. It would be helpfulhere to have one line of type as set for printing. If this is notenough, have one pupil stand in front of a good sized mirror.Then have him tell a pupil to stand behind the mirror where hisimage appears to be and in the same apparent position..Thenremove the mirror and have them shake hands.So far the teacher has developed inductively how images are

formed and the characteristics of the image. A vocabulary needsto be developed through the use of the textbook. Word study isvery important in science.In this laboratory activity the emphasis has been placed on

the what and how of science�not the why. In all of the ac-tivities so far the pupils have stood directly in front of the sur-


faces. Now place some object to the right of a mirror (45°) andhave some one locate the position where the image of the firstobject may be observed. Change the position of the first objecttwo or three times. Next place a pencil at an angle with a mirror.Then place a second pencil so it appears to be in a straight linewith the first pencil as observed in the mirror. Pupils will soonlearn something akin to saying the angle of reflection equals theangle of incidence. Next have them arrange their mirrors toreflect sunlight to some spot on a side wall and then to the ceil-ing. Here is their opportunity to apply what they have learned.The pupils are now ready to take up double reflection by

placing a candle between two mirrors which are parallel to eachother. Then arrange two. mirrors so a pupil can see the back ofhis head, as is done in some stores. A simple periscope can alsobe made.

If the room can be darkened and the teacher has a flashlightor lantern that will project parallel rays of light, some worth-while demonstrations may be performed. Hold the lantern sothe rays of light will strike the following objects at the anglewhich will reflect the light to the ceiling. First use a mirror, thenplate glass, translucent glass (both sides) white, black and bluepaper, surface of water in a dish, then shake the dish. Thesedemonstrations will help pupils learn which surfaces reflect lightwhich diffuse light, and which absorb light. Then the problemof glare can easily be demonstrated.Now the teacher is ready to begin the development of real

images with the use of concave mirrors. This may be done by afew simple demonstrations. Many more activities may beplanned if several curved mirrors are available. Then to reflec-tors on lamps, automobile headlights, beacon lights, the newtrain lights, and the reflecting telescope. The activities withcurved mirrors in forming different kinds of images will be anintroduction to the study of images with lenses which will comelater.Out of all of these activities many questions will be raised by

pupils. Many of these questions can become the basis for realproblems and projects. They may be solved by pupils individu-ally or in small groups.The controlled experiment is the second type of activity that

needs more emphasis. It is not difficult to plan demonstrationsso several factors may be introduced into an experiment. Inevaporation a teacher may use different sized dishes, different


liquids, different temperatures and with varying amounts of aircurrents. If carefully planned, the results will be contradictoryas far as any one factor is concerned. As a result, pupils will ob-serve that the rate of evaporation may be affected by surfacearea, temperature, winds or the nature of the liquid. Here wehave four possible variable factors. The class may be dividedinto four groups with each group being responsible for discover-ing the effect of one factor on the rate of evaporation. Eachgroup will need to control the other factors. After each grouphas completed its plans, they are read to the class. Then all ofthe groups will need to plan the controls for all the experiments.

If A is the only factor that is allowed to vary in an experiment,then factor A must produce the result, if there is a result. Herethe chance of knowing what factor produced the result is 1 in 1,or certainty. It is simplicity itself. If factors A and B are allowedto vary at the same time, then the results, if there are any, maybe produced by A alone, by B alone or by the combination of Awith B. Here the chance of knowing what factor or factors pro-duced the result is one in three. This is very little better thanguessing, if any better. If three factors are allowed to vary atthe same time, the chance of knowing what factor, or combina-tions of factors, produced the results is one in seven and for fourfactors it is one in fifteen.

Pupils can learn to plan a controlled experiment without anygreat difficulty. There is marked improvement in the secondexperiment and still more improvement in the third. It is notnecessary to perform more than three or four a year to havepupils learn how to experiment.Can pupils detect faulty experimentation as reported in ad-

vertisements and over the radio? If you do not think they can,then bring in copies of advertisements in which some photo-graph, diagram or description tells how an experiment was per-formed. The lack of carefully controlled experimentation iseasily detected. Dishonest advertisers know people believe inthe results of experiments. The descriptions of their so-calledexperiments are planned to deceive people rather than give thetruth.

I believe most of you are familiar with the other types oflaboratory activities which have been suggested. All worthwhilelaboratory activities must be carefully planned or initiated sothat pupils will have direct contact with materials and will learnhow to use the most important inventive discoveries the human


race has developed. These are the great inventions they useevery day. These are the things that make modern living possi-ble. We must then do everything possible to see that pupils aregiven the opportunity to study science in well equipped labora-tories, and with teachers who are always conscious of the greatpossibilities laboratories have to offer.

THE QUIZ SECTION

JULIUS SUMNER MILLERChapman College, Los Angeles, California

1. Rodents are gnawing animals. (T or F)2. If water is boiling gently it is just as hot as when boiling vigorously.

(T or F)3. Neon forms no known compounds. (T or F)4. Who said: "If I have seen farther than other men, it is because I have

stood on the shoulders of giants"?5. All the planets and asteroids revolve around the sun in the same di-

rection. (T or F)6. White sand (SiOz) mixed with limestone (CaCOs) and sodium carbon-

ate (NazCOa) and highly heated yields what common substance?7. The eye accommodates for distance by changing the curvature of the

lens. (T or F)8. The shape of the Big Dipper is constant and fixed. (T or F)9. Neutrons can be accelerated by an electrostatic field. (T or F)

10. The primary bow (of the rainbow) is red on its outer side. (T or F)11. Pi does not satisfy any polynomial equation with integral coefficients.

(TorF)^12. The logarithm of 1 to any base is zero. (T or F)’

13. What is the coccygeal region?

ANSWERS TO THE QUIZ SECTION

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a plan for laboratory activities in general science

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