Science Teaching With Self Apparatus

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Science Teaching with Self-made Apparatus(*).

P. G. Michaelides, Professor at The University of Crete, [email protected]

Tsigris Miltiadis, Chemist Teacher assigned to The University of Crete, [email protected]

(*) This work has been partially financed by the European Commission (project Hands-on Science contract number 110157-CP-1-2003-1-PT-COMENIUS-C3). The views expressed represent the authors. Neither the

European Commission nor the authors may be held responsible for any use of the information provided here.

Abstract . The laboratory practice, for thestudents of the Pedagogical Departments and the for the schoolteachers, constitutes an important presumption for the future teaching of Science inthe schools. Self made apparatus, especiallywhen used in measurements, give the students,the ability to have an integrated control of theexperimental steps, to improve their searchingcapabilities and to induct conclusions, throughthe measurement and the manipulation of their errors. Some examples of self made apparatus

from different areas of Physics, are described in

this work together with hints on their incorporation to the Teaching of Science.

Keywords. Self-Made Apparatus, ScienceTeaching, Measurements.

1. Introduction

Literacy in Science and Technology (STL) isfundamental for the welfare of modern,technology dependent societies. As more andmore of the regulations of modern, technologydependent societies are based on the advances inScience and Technology, the basic constituent of democracy, i.e. citizens participation, requiresSTL. In this sense, STL becomes a right todemocracy, a view also pursued by UNESCO.Within this framework Science Teaching ingeneral education should be based on principlesand methodology rather than on factualknowledge [1] and poses specific demands onthe skills and knowledge of the Science Teacher[2]. A sound knowledge of the basic principles is

considered, in general, a prerequisite for theScience teacher. Although teachers in PrimaryEducation, at least, lack this knowledge, our

experience shows that a major problem hinderingthe effectiveness of Science Teaching is theteachers attitude towards Science; in generalthey should change their approach from factualknowledge on specific data, techniques andthemes or from the successful performance of an experiment, towards a scientific inquiryapproach [3], in which, in accordance with aPiagetian context, Science knowledge is notacquired by the student but it is discovered or, atleast, negotiated anew. This teaching approach isheavily dependent on systematic Science

observations and experiments and this makesexperimentation a basic required skill of theScience teacher. In this work we discuss oneparameter (the use of self-made apparatus) of experiments in Science teaching. We also presentexamples from different areas of Physics.

2. Assumptions

In experiments, the use of sophisticatedcomplex equipment may give accuratemeasurements. However, it removes theauthentic creative activity and converts theexperiment to a demonstration process in whichthe student observes the results of an apparatushe-she does not understand. This, combined withthe general attitude to get the results of theexperiments instead of inquiring a situation of aNatural phenomenon, hinders, at least in generalScience, the understanding of the phenomenonunder study. Even teachers with a soundscientific knowledge lack, in general, the skill totransform their scientific knowledge intoteaching practice [4]. As a consequence, Scienceand Technology are considered as difficultsubjects [5] although they are rather simpler (as

Paper presented at the 1 st Inernational Conference on Hands on Science Hsci2004 Teaching andLearning Science in the XX1 Century, 5-9 July 2004, Ljubljana, Slovenia, Proceedings pp.47-52http://www.hsci.info/hsci2004/ .


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may be inferred from the fact that, in humanhistory, they appear and advance earlier thanother sciences) and possess inherent advantages.For example their subjects of study are easilyperceptible through the senses, an irrefutableadvantage for most of the compulsory educationstudents who, in a Piagetian context, have not asyet reached the formal logic stage. Thisconstitutes a significant problem in most of theadvanced countries. The construction, totally orpartially, of the apparatus to be used inclassroom Science experiments is a very creativeprocess associated with the development of cognitive and psycho motive skills and facilitatesthe logical process of induction. In a groupwork construction, the development of social skills isalso facilitated while the pleasure of creation

covers the sentimental sector. The use of self-made apparatus exhibits also other inherentadvantages; it facilitates query situations and theprocess of planning an experiment; itdemonstrates an immediate application of someof the relevant Science issues; it removes theblack box feeling often associated with the useof modern hi-tech devices; it develops theingenuity of the teacher, especially the primaryschool Science teacher for alternatives to theusually expensive equipment on sale; it alsomakes clear the discrimination between

observations data and their interpretation [9].Incorporated into the education of the ScienceTeacher, the construction of self-made apparatusto be used in Science experiments is anotherexample of polymorphic practice [10] andfacilitates the transformation of scientificknowledge to school practice.

3. Principles and examples

In order to be useful to Science Teaching, theconstruction of self-made apparatus must followsome principles, in accordance to the contextexposed previously, i.e.:

3.1. Simplicity and Safety

The construction must be simple. Thematerials used must be easily available from theeveryday environment of the school and thestudents. The assembly should be within theabilities of a do it yourself layman. During theconstruction process, dexterities and knowledge

on the properties of the materials used and onhow to handle them become a clear task. Simpleconstructions facilitate the understanding on the

apparatus functioning and minimizes safetyproblems. Safety is always an important issuethat must be stressed, even over emphasized.When students, especially children are involvedthis statement is obvious; it helps also to thedevelopment of good safety awareness attitudes.The situation is also similar for teachers,especially teachers in primary schools who, ingeneral, lack a professional training in Science.

3.2. Problem solving

The whole process must provoke theingenuity and creativeness of the students. Onthis basis, the guidance offered must remainwithin the general goal, leaving the initiative tothe student. Detailed guidance should be limited

to specific queries related to technical orspecialized issues.

3.3. Accuracy, sensitivity and calibration

As the prime goal is to understand theprinciples (natural law) involved, high levelsof accuracy are not required. The apparatusconstructed, however, if used as a measuringinstrument, must be accurate with an appropriatesensitivity. Calibration is a necessary step forapparatus used as measuring instruments.

Usually it is done by comparison with aprofessional instrument but a discussion on theprinciples used to make the standards is veryenlightening. Estimation of the accuracy anderrors is very helpful on the conceptual meaningof measuring errors and their treatment.

3.4. Assessment

When the construction is finished, aretrospective evaluation on the whole process, onthe choices made and on the other possiblealternatives and, also, a comparison withapparatus made by others is advised. Itrecapitulates on the subject under study andfacilitates meta-cognitive effects. Althoughhighly subjective, aesthetics of the finalconstruction is an important issue mainly fromthe viewpoint of practicality and as an indicationof deliberation and diligence.

4. Some examples

In the following we present some examples of self-made apparatus. All have been realized inthe Department of Primary Education of the


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University of Crete within the normal teachingactivities in Science. For a couple of them noteson their usage within teaching are also given.

4.1. Gas Thermometer

The task is to construct a thermometer.Additional aims include basics on glasstreatment, a useful skill for chemistryexperiments, the notions of calibration, accuracyand sensitivity of measuring instruments and of the measurement error. The construction isshown schematically in Fig 1. A glass test tube

(similar to the ones used in chemistry) is heated(a). When the glass is soft enough we elongatethe tube with a quick steady straight outwardmotion (b). We cut (break) the glass near theopen end of the test tube (c), the result being abulb chamber with a thin elongated pipe. This isa device with many uses (see also later on).When the chamber is warm to the highesttemperature range we plan to use thethermometer (e.g. by holding the chamber in our

warm palm), we touch the open end of the pipeto a drop of coloured water (d) leaving thechamber to cool so that the coloured drop entersthe pipe. We fix the device on a piece of cardboard (e) and proceed to calibration.Calibration is achieved by immersing thechamber into water of different temperatures sothat the coloured drop inside the pipe traversesthe whole length of the pipe. Although the twoextreme temperatures would be sufficient,because the pipes cross section is not constantone or two intermediate points are necessary.Intermediate temperatures may then be noted toconstruct the scale. During the construction the

(unsuccessful) trials are a good starting point fora glass handling dexterity. Observing thecoloured drop dropping into the chamber orgoing out of the open end of the pipe when thetemperature is too low or too high for thespecific construction, a discussion on the rangeand the parameters it depends may be initiated.Observing differences between differentconstructions may arise in a discussion on themeasuring errors. Checking repeatedly theaccuracy of this thermometer against a standardone may unveil the dependence on theatmospheric pressure which may lead to animprovement, for example, another bulbchamber on the open end.

4.2. Hydrometer

The construction is similar (Fig 1 point c) asin the Gas Thermometer discussed previously.For calibration purposes however, the pipeshould not be too thin. Having the device shownin (a) of Fig 2 put into it small lead balls (e.g.thin shot) or even sand and immerse it intoliquids of different densities so that the chamber

of the device is totally immersed into the liquid

while the pipe is either outside (as in b in Fig 2 a relatively dense liquid) or inside the liquid (as

Figure 1. Gas Thermometer

Figure 2. A Hydrometer


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in c in Fig 2 - a relatively thin liquid). By fixingthe device into a cardboard the scale may bedrawn and then the open end of the pipe is sealedwith a gas flame. Liquids more dense than watermay be prepared by dissolving salt into waterwhile liquids less dense than water may beprepared by mixing alcohol spirit with water. Inboth cases the density may be determined byweighting a known volume (e.g. through avolumetric cylinder) of the resulting solution.The device may be used to measure the densityof different liquids, for example wines and spiritsor must and infer the alcoholic content. Thisconstruction, especially the calibration process,is advantageous to the understanding of density,of the different ways of titration of solutions, etc.

4.3. A weighing-machine

This device (see Fig 3) may be used for theteaching of mechanical moments. Theconstruction is made with materials used to hangslide curtains in house windows. The weight, W,

hangs from a hook used to hold the curtainwithin the slide rod. Similar hooks are used forthe joints in p and s. The educational value of this device is in the process of calibration wheredifferent aspects on the mechanical momentsmay be clarified. The construction, if done withdiligence, may be very accurate. It is also used in

other apparatus (see for example Anamperometer later on).

4.4. An amperometer

The construction (see Fig 4) is based on theweighing machine discussed previously. The

plate has been replaced by an iron washer fixedon the balance rod and a coil around an iron bolt.Connecting the coil serially to an electric circuit,the current induces an electromagnetic forcewhich holds the washer to the bolt. Moving theweight along the rod the electromagnetic forcemay be measured by comparing thecorresponding mechanical moments. The mainobjective of the variation presented here is tohelp understanding the electromagnetic forces.An adaptation could be the following: replace theweight by a (coil) spring. Fix the bolt in the placeof the washer. Increase the height of the rodsupporting the balance rod. When theelectromagnet is activated the bolt is attractedinto the (hollow) coil and the correspondingforce may be measured by the elongation of the

spring. By fixing the spring in different distancesfrom the supporting the balance joint, differentcurrent ranges may be measured.

4.5. Geographical coordinates

The device needed is a simple vertical rod OAon a flat horizontal surface (see Fig 5). Duringthe day we mark the end of the shadow of the rod(the s points in Fig 5) together with the time anddraw the corresponding line. For demonstrationpurposes the s-point line is shown curved. Inpractice it is almost a straight line. The pointB of the line which is the smallest distance fromthe rod determines the local meridian (thedirection O to B is the North direction forlocations in the northern hemisphere). The timethe shadow of the rod is along this OB directionis the local noon time and determines theLongitude of the place. For example forRethymno-Crete, Greece where political time isGMT+2hours, if local noon occurs at 12:22 localpolitical time, the Longitude is 2 (because of the2 hours difference from Greenwich mean time)times 15 arc degrees minus 22 (the 22min in12:22 local time noon) times 15 arc minutes, thatis 24.5 arc degrees. The corresponding angle is related to the local Latitude. It is equal to theLatitude on the equinoxes (21st of March and23rd of September). On the solstices, the angle takes its extreme values, Le, where L the locallatitude and e ~23.5 arc degrees is the obliquityof the ecliptic. A plot of the angle versus theday of the year is periodic with extremes at the

solstices and may be used also to determine thebeginning of every season i.e. the days of the

Figure 3. A weighing/machine

Figure 4. An amperometer


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solstices (23rd of December and 21st of June)and of the equinoxes (21st of March and 23rd of September). This simple construction and thecorresponding measurements may help inclarifying the generally difficult subject of therelation between Earths movements and theseasons, etc. It also offers a good example on themanipulation of the original measurements, toget results with an estimation of themeasurement error. Using advancedmathematical processes very accurate resultsmay be obtained for the estimation of local time(and thus of the Longitude of the place) and of the angle (and thus of the latitude of the place).However, the results may also be obtained withadequate precision of the order of 0.5-1 arcdegree and the beginning of each season with a

precision of 1 day with the sole use of graphs.

4.6. More examples

The main objective of the self made devicesexposed previously is to make a workingconstruction that will help the understanding of the concepts involved. Making measurementswith an adequate precision is also feasible. In theweb site http://www.clab.edc.uoc.gr/hsci otherexamples are given [13].

5. Epilogue

The self-made constructions, examples of which have been presented in this work, have allbeen used during the teaching of Science and/orScience Teaching courses in the Department forPrimary Education of The University of Crete.All of them have been realized as assignedprojects by students subscribing to the relevantcourses. These constructions have thecharacteristics of Polymorphic Practice andmany of them have also been realized partially ortotally by school students. Some indicativeresponses from the University students are:

I imagined that for Science experiments aspecial laboratory was necessary but Irealized that doing experiments is not socomplicated a matter.

I learned to work on my own (a commentmade more often by female students).

I realized that what we had learned in schoolmay have direct applications.

What I learned can be used directly toschools.

The construction helped me to understandwhat I had only memorized.

I realized that there is a difference betweenthe graphs in the Science books and theactual data obtained (referring to thescattering of measurements due to

measurement errors, a fact usually absent inthe graphs of textbooks).

However, there is a significant percentage of students that drop out of the courses. The reasonsmay be pursued in the direction of the followingcomments:

It was difficult but I learned to work on myown.

A good course, but the effort I made wasworth of two or more other courses.

In conclusion, the experience is very positive.Students comments, in schools and in theUniversity, show an acquired positive attitudetowards Science, an increase of their self-esteemand confidence on their abilities and an increasedinterest in Science [14].

9. References

[1] P. G. Michaelides, "Everyday observationsin relation to Natural Sciences in Learningin Mathematics and Science and EducationalTechnology, University of Cyprus July2001, Volume II pp. 281- 300.

[2] P. G. Michaelides, Polymorphic Practice inScience", pp 399-405 of the proceedings of

Figure 5. Geographical Coordinates


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the 1st Pan-Hellenic Conference on theDidactics of Science and the introduction of New Technologies in Education, Universityof Thessaloniki, Thessaloniki May 29-31,1998 (in Greek).

[3] Lillian C McDermott, Peter S Shaffer and CP Constantinou, Preparing teachers to teachphysics and physical science by inquiry,Phys. Educ. 35(6) November 2000, pp. 411-420

[4] Krystallia Halkia, Difficulties inTransforming the Knowledge of Scienceinto School Knowledge, pp. 76-82, of Vol.II of the proceedings of the University of Cyprus, 1st IOSTE Symposium in SouthernEurope Science and TechnologyEducation: Preparing Future Citizens,

Paralimni-Cyprus 29/4-2/5 2001.[5] Piaget (the future of Education) assigns thisdifficulty in relation to Science whilestudents are performing well in the rest of the subjects to the type of instruction offeredwith a more probable cause the fast passagefrom the qualitative management of naturalproblems to the quantitativemathematization through the use of PhysicalLaws that enter the instruction in thestudents absentia.

[6] P. G. Michaelides, Understanding

difficulties in Science observations, oralpresentation, 2nd Pan-Hellenic Conferenceon the Didactics of Science and theintroduction of New Technologies in

Education, University of Cyprus, NicosiaMay 3-5, 2000 , book of abstracts page 26(in Greek).

[7] See [2]. Polymorphic practice(measurements, experiments...) in Scienceincludes a common psycho motive activity(doing measurements, experimentation...)which consequently is morphed intodifferent levels depending on the (previous)cognitive attainment and/or the mentality of the students. They resemble multilevelteaching i.e. teaching pursuing more thanone sectors and levels of learning. The needfor polymorphic practice teaching arisesusually in the training of Science Teacherswhere there is a requirement of teaching inan advanced level for the teachers

themselves, and the requirement of teachingin a level more accessible for the pupils. Thedifference in the teaching levels is not onlyon the didactics but also on the subjectmatter and the attainment levels.

[8]This site is also used by students and is undercontinuous restructuring. Please report, by e-mail, any difficulties to access the site [email protected].

[9] Note that the majority of the Students inschools consider Science as difficult subject(see [4]). Note also that when relevant data

were collected, more than 80% of thestudents in the Department for PrimaryEducation had only the minimum requiredScience courses in school.

Science Teaching With Self Apparatus

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