Chapter XV: Part III: Science (2)

A raised model may then be shown to the class, and this may be coloured in the same way as the maps, but the children must clearly understand the disadvantages of a model, and be shown that the vertical heights are always enormously exaggerated in proportion to the horizontal distances.

In recapitulating, the children might be asked what they consider a common slope for the sides of mountains. Their notions will always be found to be extravagant, many of them thinking they have seen and even climbed slopes of 60 degrees and upwards. By placing a piece of india-rubber on the cover of a book, and gradually opening the book and sloping the cover till the india-rubber rolls off, the children may be shown how very small is the angle at which it is perfectly impossible for anything to rest on a slope, and that therefore if we find stones on the side of a hill, we know that the slope cannot be greater than 30 degrees. Examples may be drawn from any hill in the neighbourhood of the school.

_Lesson IV._ A second lesson will be necessary on the contour of the given continent, when the names of the mountain ranges and of the plains may be given, short descriptions of them read, and exercise given in filling them into a blank map from memory.

[Position of rivers.]

_Lesson V._ The teacher fills into a wall map, blank and uncontoured, the principal rivers, and asks the class to put them in their contoured maps. Many of the children will be found not to have appreciated the meaning of contour lines, but will have drawn a river flowing from the part coloured green to that part coloured brown. One such map will form a good object-lesson, and the children can be brought to see the absurdity of what they have done in representing a river as flowing up a hill.

The properly contoured wall map may then be hung up, and the actual position of the rivers followed. The meaning of watershed will now be apparent, and the fact should be noted that it does not necessarily or even generally correspond with the highest land.

The varying velocity of the river should be drawn from the children from the nature and position of the contour lines, and from that, which parts of its course are being sculptured and in which parts deposition is taking place.

_Lesson VI._ If a physical course is given, the work of rivers will already have been treated, but certain rivers in the continent should be chosen for special description. From the contour line the children will be able to say for how great a distance the rivers are probably navigable, and the uses of the given rivers as a means of communication and the position of towns on their banks may be discussed.

[Coast line.]

_Lesson VII._ Coast line. Sufficient knowledge will now have been gained to render possible the appreciation of some of the causes affecting coast line.

When rocks are hard and folded, producing mountains, then they will also give rise to rocky promontories. Clays and sands, which inland allow themselves to be worn into plains and valleys, will here produce bays. Rivers, if still capable of erosion, will produce valleys, which a slight subsidence will convert into narrow gulfs. Finally the accessibility of various points on the coast may be considered, and the position of the chief harbours and ports.

[Climate.]

_Lesson VIII._ Climate. This lesson may be treated deductively, as the class is already familiar with those phenomena upon which both temperature and rainfall are mainly dependent. The rainfall might be given as an exercise, allowing the use of contoured maps, and the chart of the prevailing winds.

_Lesson IX._ Distribution of vegetation, pastoral and agricultural districts.

_Lesson X._ Distribution of minerals, centres of population.

At the end of this course a physical map of some country not already studied by the children should be hung before them, and they should all be asked to write an essay about the country from the facts that they find in the map.

If they can do this, they will have learnt to read a map intelligently, and one of the great ends of a course in geography will have been attained, since they will not only have acquired many new facts, but have also gained the power of searching for and assimilating facts for themselves.

When England is the country being studied, this course must be supplemented by more detailed work on the causes that have determined the positions of cities and towns, and how these causes have operated during the last 2000 years. The children should be shown that British camps were generally on escarpments overlooking the surrounding country. The district round was cultivated, and the inhabitants sought safety in the camp in time of danger. After having been told that the position of some of these “duns” or hill forts is still indicated by such place-names as London, Dunstable and Dundee, the children might be encouraged to suggest other places themselves. The number of camps was greatly increased by the Romans, many of the sites being marked by corruptions of the Latin word _castra_, as Chester, Colchester and Winchester, and these camps were joined by well-made roads.

Later immigrants formed their centres either in the neighbourhood of these roads, as the Saxons, who often formed villages at a point where the road crossed a stream, as Hertford and Stamford on the Ermine Street, or on sheltered bays and navigable streams, like the Norse and Danes, whose towns and villages, ending in “ley,” “thorpe,” “wic,” are never found except where there is a spring or other natural water supply.

As the various races inhabiting England became amalgamated, and the land was cleared, there was a tendency for towns and villages to spring up over such districts as the Weald, the eastern counties, the central plain and broad river valleys. But there was no great concentration of population save in the south-east, where the neighbourhood of the continent called into existence the Cinque Ports, and where iron smelting was carried on by using the wood of the Wealden forests.

As the Cinque Ports declined, the growth of the navy and the increase of fisheries and trade with the continent increased the size of other ports, and the growing importance of the woollen trade called into existence the large Norfolk towns, which flourished until vexatious guild regulations induced many workers to leave the towns, and form industrial villages as Manchester, Birmingham and Sheffield. Settlements of foreigners, as the French silk weavers at Spitalfields, also formed a nucleus for other industries.

At this point the children might be shown a geological map of England, and also a map in which all those districts with a population of more than 500 to the square mile are coloured red; they would notice that almost all these red patches correspond with coal fields, and be told that the period of beginning to work many of these coal fields, corresponded with that at which America was being opened up; that consequently such ports as Liverpool and Bristol on the west coast became identified with the importing of cotton and sugar, and that towns engaged in these industries sprang up in the neighbourhood of these ports.

The use of steam power in various manufactures still further attracted the cotton and woollen industries to the towns of Lancashire and Yorkshire, and the working of iron, found in the neighbourhood of coal, accounts for many other centres of population.

Another map may now be shown with the various manufacturing towns marked, and attention called to the physical features which have caused the location of the industry at that spot, as the presence of water power, the possibility of water carriage, the neighbourhood of a port, the presence of hard water used in beer-making, as at Burton.

When the internal growth of England has been considered, a lesson should be given on her commercial supremacy, and the factors which have determined it. England’s position in the centre of the great land hemisphere, the climate, the indented character of the coast, and the mineral wealth, should all be touched upon; nor in doing this should points not geographical be omitted, as the needs of a continually increasing population, the founding of colonies by a part of this surplus population, and, above all, the character of the people, upon which alone the greatness of an empire can rest.

PHYSICS.

By AGATHA LEONARD, B.Sc. (Lond.).

[Position of “physics” in scheme of science teaching.]

As a preliminary to any remarks on the teaching of physics, it will be well to consider the place which the subject should hold in a general scheme of science teaching. It is not the most suitable subject for junior classes; for young children the sciences of botany and zoology which cultivate the observing faculty, while making less demand upon the reasoning powers, are preferable, but for children of thirteen or fourteen a course of elementary physics affords valuable training and arouses great interest. The subject must, of course, be treated on purely experimental and non-mathematical lines, indeed the chief value of physics at this stage is to teach the children the true use and nature of experiment. They will probably begin with the idea that the use of experiments in a lecture is somewhat the same as that of illustrations in a story-book, to render it more entertaining, though they might be dispensed with, and it takes time to make clear to them that experiment is the very groundwork of all science, the careful “questioning of nature” as to what effects follow upon certain causes. These lessons on physics will lay an excellent foundation for a course on physical geography, which may be taken for the next year’s work.

With girls of fifteen or sixteen either a second course of physics, involving a knowledge of elementary mathematics, may be taken, or chemistry may be begun; while with older classes the choice of a subject will greatly depend on the nature of their previous work, and on the facilities for laboratory work in chemistry or physics. Physiology should not be taken with girls below sixteen; it is of less educational value than either of the subjects above-mentioned, the possibility of personal observation being less, and the whole as taught in schools too often a matter of memory rather than of observation or reasoning; if taught to elder girls it is rather for the practical advantage of the information imparted than for scientific training. Some such scheme of science teaching throughout a school as the following might therefore be suggested:--

Classes of average age 10 to 12 Botany or Zoology.
„ „ „ 13 „ 14 Elementary Physics.
„ „ „ 14 „ 15 Physical Geography.
„ „ „ 15 „ 16 { Chemistry or Physics (Magnetism and
{ Electricity or Heat and Light).
{ Chemistry or Physics or Botany;
Senior Classes { Physiology and Hygiene (in addition
{ to one of the above).

The first course of physics (see end of chapter) may deal with some of the chief forces of nature (gravity, cohesion, friction); the three states of matter and their properties, under which head would come lessons on atmospheric pressure; elementary ideas of work and energy; and the simple phenomena of sound and heat. The subject of light is better omitted until sufficient knowledge of geometry has been acquired to allow of the laws of reflection and refraction, and the effect of prisms and lenses being rather more adequately dealt with than is possible at this stage. Magnetism and electricity also are better postponed until a later course.

[Home-work.]

No text-book should be given to the children, as their home-work in science should never take the form of learning from a book. Some teachers, to avoid this, let the children take notes, and attempt to reproduce the lesson, others give, either on the blackboard or by dictation, a clear summary which the pupils take down verbatim, but neither plan is satisfactory; the first leads to confusion and inaccuracy, as the children are not old enough to take good notes, while under the second all the work is done by the teacher. I have found it best to end each lesson by setting some questions, framed so as to bring out the chief points of the lesson, to be answered by the children in their own words. The answers must be carefully looked over and criticised at the next lesson, and a methodical account of experiments insisted on, specifying in order the object of the experiment, the apparatus employed, the method adopted, and the results obtained and conclusion drawn. Specially good passages may be read to the class, both as an encouragement to the writer, and as an example to the rest of what can be done by one of themselves; and special censure should be given to careless work, but great care must be taken to avoid confusing mere mistakes with “bad work”; the children should be made to feel that more value is attached to even faulty explanations or descriptions, which show that their minds have worked on the subject, than to the most perfect reproduction of the teacher’s exact words.

Besides the advantage of securing that the pupils and not the teacher shall do the main part of the home-work, the teacher may gain most valuable hints from the errors of the children; they will be found often to arise from some misconception, the removal of which will suggest a quite fresh method of explanation; indeed a teacher will be unlikely to succeed in imparting clear scientific ideas to her pupils who is not on the watch for any indications of what ideas, right or wrong, they really have formed, and able therefore to see their difficulties from their point of view.

[Definitions.]

The only case in which knowledge may perhaps with advantage be cast into words not by the pupil alone but by the teacher, is that of a definition, the construction of a concise and accurate definition being in most cases beyond the child’s unaided powers. Even here, however, the child should do as much as possible of the work herself, only it should be done in class with the teacher’s help instead of at home alone. Thus, suppose the lesson to be on the three states of matter, it is better not to give a definition of each as the starting-point, and then go on to illustrate and explain the same, but to start from the undefined idea which every child possesses of a solid, a liquid, and a gas, and develop from it by degrees the precise definition. Suppose the class to suggest as definitions that substances in the solid state are “hard,” in the liquid state “wet,” and in the gaseous state “invisible,” they will be much interested in having the imperfection of these definitions brought home to them by the help of the liquid metal mercury, which does not “wet” glass or porcelain, and of the visible gas chlorine, and in being led to find out the true distinctions by observing the different behaviour of solids, liquids, and gases respectively when placed in vessels of differing shapes and sizes.

[Science teaching not “authoritative”.]

It must indeed be a fundamental principle throughout these lessons to tell as little as possible; not only should the children produce unaided reports of their work, but the reports should be of what they have themselves observed, not of what they have received on authority. The worthlessness of authoritative science teaching is very generally felt in these days, and some modern teachers are disposed to deny any value at all to science lectures for young children, asserting that _only_ by experimental work carried out by themselves, with as little interference from the teacher as possible, can any really scientific ideas be communicated to them. The value of personal practical work I, of course, fully admit, but I am sure that really “scientific” training may also be given in a “lecture” lesson, by a teacher who knows her subject, and is skilful in the art of questioning, and in making her children tell her what they really do see in an experiment, instead of telling them what they ought to be seeing.

That observation may thus be trained, it is of importance to secure that all experiments shown to young classes should “go”. With older classes the occasional failure of an experiment may be no great matter, they are capable of understanding that the conditions of the experiment were not fulfilled and hence the failure, but with beginners in science it is very undesirable to produce the impression that when Nature is “questioned” she sometimes gives one answer and sometimes another. Experiments that cannot be shown to the children should as a general rule not be described, though when any principle is thoroughly grasped and driven home by experiments performed before the class, there is no harm in mentioning as additional illustrations such phenomena as the falling of the mercury in a barometer tube on being carried up a mountain, or the impossibility of making good tea at high altitudes owing to the lowering of the boiling-point of water; but should the want of apparatus prevent an experiment otherwise suitable for a lecture from being performed it is generally better with beginners to omit all mention of it.

[Apparatus for elementary course.]

For carrying out such a course as that now being considered very simple and inexpensive apparatus is for the most part needed. The only expensive piece really necessary is an air-pump; for the rest, an ordinary pair of scales, a few glass beakers, flasks and funnels, some glass tubing and rods, a little mercury, some wire gauze, some sheet india-rubber, thermometers, a Bunsen burner, and a retort stand or two, are all that is needed, though the addition of such pieces of apparatus as the Magdeburg hemispheres will enable interesting experiments to be shown.

[Practical work.]

As regards the children’s own practical work it is not always possible to arrange in schools for laboratory work for beginners; the time at disposal is often insufficient, and the class too large for a single teacher to give the supervision needed by children so young; but where the class can be taken in sections of not more than ten or twelve pupils for an extra lesson, nothing so greatly rouses the children’s interest and gives so real a grasp of principles as a course of simple experimental work carried out by themselves. Accuracy must be insisted upon from the very beginning; each experiment must have a definite object, and a description of the experiment with the results obtained must always be written out by the child. It is a good plan to give as many experiments as possible in which the result aimed at is quantitative, it is a great satisfaction to a child to obtain a result whose correctness can be gauged, but it is not necessary that the work should be exclusively of this type. The course may begin with the careful measurement of lengths, employing different methods, such as the direct application of the rule to the object, the transference of distances by means of compasses, and obtaining the lengths of curves by means of a string laid along them and afterwards measured; and the children should be taught to make measurements on the metrical system as well as in feet and inches, especially if they already possess any knowledge of decimals. When they can measure as accurately as their scales will allow, the vernier may be introduced, its principle explained by the aid of a large-sized model, and practice given in reading the verniers on barometer scales, etc. Then may follow measurement of the area of rectangles, and, if the children’s mathematical knowledge allow of it, of triangles and other rectilineal figures, then the determination of the volume of rectangular solids from their linear dimensions. The determination of mass may next be taken up, and the pupils taught how to use a balance properly, the C.G.S. unit being again employed as well as the pound; then they may learn how to weigh in water, and how to prove experimentally that the loss of weight of a body weighed in water is equal to the weight of the displaced water; then the volume of a body may be determined by finding the mass and hence the volume of the water it displaces; from this they pass readily to the determination of specific gravities. Experiments on air pressure may follow; the children may learn to read the height of the barometer, and to make for themselves barometric charts showing the variation of the height from day to day; this affords a good opportunity of teaching them to use squared paper. There are also many simple experiments in mechanics, such as the experimental determination of the principle of the lever, the finding of the position of the centre of gravity of a lamina, the finding of the resultant of two parallel forces, etc., very suitable for such a class. Then may come easy experiments and measurements in heat, the reading of various thermometer scales, the filling of a thermometer and its rough graduation, and experiments proving the fact of expansion and of the force exerted by expanding or contracting bodies; measurements of the amount of expansion are too difficult for this stage. Much supervision is required; special care should be taken that children are not left with unoccupied intervals during which they get listless and bored; this requires careful previous planning out of sufficient experiments for the whole class. It will stimulate interest if several children in succession are allowed to make the same measurement, and then to compare their results.

Even where no laboratory class is taken, the teacher can still take opportunities of convincing the children that experiments can be performed by themselves as well as by their class-teacher; they enjoy being called up to perform an experiment in class, and will, if they have any taste for the subject, take an interest in repeating any possible ones at home; they can convince themselves of air-pressure by private experiment with syringes, siphons, and inverted tumblers, or can find centres of gravity, or experiment with sounding strings of various lengths, but of course such desultory experiments, followed by no careful writing out of results, do not give very valuable training in scientific accuracy.

[Diagrams.]

I would insist also on the importance of requiring children from the first to illustrate their work by diagrams; a little time is well spent in criticising these, and in showing how they might be improved. Very neat and serviceable diagrams may be produced even by children with no natural taste for drawing, but they need to be shown how to work, and perhaps to have the lines of a diagram suggested to them at first by a rough blackboard sketch, or it may not occur to them that a few simple lines will show all that is necessary better than a would-be realistic sketch of apparatus, with impossible perspective and smudgy shading.

[Course of electricity and magnetism.]

I pass on now to somewhat higher classes. With pupils whose average age is about fifteen, some one or two of the branches of physics may be taken more in detail. Suppose electricity and magnetism to be chosen, the aim throughout the course should be so to impart elementary ideas that they may be a real help and not a hindrance to any future effort to take in modern views of electricity. To this end attention should from the very first be directed to the electric or magnetic “field” about any charged or magnetised body and not exclusively concentrated upon that body itself, and the pupils should be accustomed to attribute the motions in such fields not to the “action at a distance” of a charge, a pole, or a wire carrying a current, but to the special condition of the medium immediately around the moving body. The idea of a magnetic field is more readily grasped by beginners than the corresponding idea in electrostatics, owing to the ease with which the field may be mapped to the eye by means of iron filings, or by marking down successive positions of a tiny magnetic needle; it seems to me, therefore, well to begin with the study of magnetism, rather than, as is common in text-books, with that of statical electricity. From magnetism the more natural transition is to current electricity, and it will be found a good plan to take the subjects in this order, passing from the magnetic fields which surround permanent steel magnets to those which are found to exist in the neighbourhood of a wire whose ends have been joined to plates of zinc and copper immersed in a vessel of dilute acid. The existence of such fields will be proved by the magnetisation of iron round which the wire is coiled, and by the motion of permanent magnets near which it is held, and the direction of the lines of force will be inferred from the direction of such motion. The existence of the magnetic field established, the term “current of electricity” may be introduced; the children will readily understand that it arose from the idea that it was something flowing through the wire which gave it such strange properties, and that whether this is the case or not, there is a practical convenience in retaining the old terms.

Some of the practical applications of the magnetic effects of currents may now be explained, _e.g._, the electric telegraph and electric bells, and the use of a galvanometer as a current indicator. Simple experiments on the induction of currents by motion of magnets, or starting and stopping of currents may follow, it being carefully pointed out that the one essential for such induction in a coil is some change in the magnetic field in which it lies. The principle of dynamos readily follows. The heating and decomposing effects of electric currents may next be considered with their practical applications to electric lighting, and electro-plating respectively, and the attention of the children should be directed to the energy appearing as heat or as chemical separation in the two cases. If they have gone through the preliminary course they will know enough of the conservation of energy to look for the disappearance of energy in some other form, and the chemical action in the battery may now be pointed out. Some explanation of “polarisation” and of the need for more complicated forms of battery than the simple voltaic cell may be given.

Lessons on statical electricity will end the course; they may be connected with the preceding lessons by first speaking of the discharge of a Leyden jar, and that between the knobs of an induction machine as instantaneous “currents,” and going on to the state of affairs in the medium between the knobs or coatings when they are not sufficiently near for the discharge to take place; this will be made clear by going back to earliest facts known about electricity and following the ordinary course of electrostatic experiments.

[Heat and light.]

Should “heat and light” be chosen instead of electricity for this year’s course, the mode of treating the subject must depend very much on the mathematical advancement of the pupils. It is probable that their knowledge will not exceed the first two books of Euclid, and algebra to simple equations, and it will therefore not carry them very far in the treatment of geometrical optics; it will enable the laws of reflection to be intelligibly explained, and the position of the image in a plane mirror to be determined (the law of refraction may also be made clear, as the children can easily be made to understand the meaning of the term “sine”), but formulæ connected with mirrors and lenses should be left to a later stage, the changes in size and position of the image formed by a curved mirror or a lens being determined experimentally and not by calculation. A general explanation of the action of optical instruments, telescope, microscope, spectacles, etc., can be given, without exact calculations, and illustrated either by carefully drawn diagrams, or by models with lenses of cardboard and rays represented by strings. The interest of lectures on dispersion and the spectrum is greatly increased if they can be illustrated by lantern experiments. The subject of heat lends itself better to non-mathematical treatment, and is specially good for practical work by the pupils themselves.

[Work of senior classes.]

[Independent reading.]

The work of senior classes, _i.e._, girls of seventeen or over, depends so much upon circumstances, such as their previous training, their mathematical knowledge, etc., that it is difficult to say much to the point about it, but a word may be added on a very common fault of such classes, a tendency to rely too much on their teacher and their notes of lectures, and to read and think too little for themselves. The practical work, which is an essential for such classes, does much to encourage self-reliance, but besides this they should from time to time be given some reading to do on points which have not been previously made clear in lectures; difficulties met with in the reading should be brought up at the next lesson, when the teacher will either solve them or put the pupil in the way of doing so for herself. This kind of work takes time, and is therefore apt to be crowded out from a full time-table, but it is worth an effort to find a place for it.

LIST OF SOME BOOKS USEFUL FOR TEACHERS.

I. PRACTICAL PHYSICS.

For Beginners--

_Inductive Physical Science._ F. H. Bailey. Heath & Co., Boston,
U.S.A.

_Practical Lessons in Physical Measurement._ A. Earl. Macmillan. 5/-.

_Exercise Book of Elementary Practical Physics._ Arranged according
to Head Masters’ Association Syllabus. R. A. Gregory. Macmillan.

For rather older Classes--

_Elementary Physics._ Henderson. Longmans, Green & Co.

_Elementary Practical Physics._ W. Watson. Longmans, Green & Co.

_Intermediate Course of Practical Physics._ Schuster & Lees.
Macmillan.

For Senior Classes--

_Practical Physics._ Stewart & Gee. Macmillan.

_Practical Physics._ Glazebrook & Shaw. Longmans, Green & Co. 7/6.

II. THEORETICAL PHYSICS.

_Primer of Physics._ Balfour Stewart. Macmillan. 1/-. (May suggest a
course for beginners.)

_Heat._ H. G. Madan. Longmans. 9/-. (A good course for junior
classes.)

_Elementary Treatise on Heat._ Garnett. Deighton, Bell & Co. 4/6. (A
good course for rather more advanced students.)

_Light._ A course on Experimental Optics. Lewis Wright. Macmillan.
(Suggests good experiments, especially with lantern.)

_Elementary Lessons in Electricity and Magnetism._ S. P. Thompson.
Macmillan.

For Senior Classes--

_Theory of Light._ Preston. Macmillan. 15/-.

_Theory of Heat._ Preston. Macmillan. 17/-.

_Electricity and Magnetism._ Foster & Atkinson. (Based on Joubert.)
Longmans, Green & Co. 7/6.

_Theory of Heat._ Clerk Maxwell. Longmans, Green & Co. 4/6.

COURSE OF ELEMENTARY PHYSICS.

DEFINITION OF PHYSICS.

Distinction between physical and chemical phenomena.--Iron heated,
Iron rusted. Candle melted, Candle burnt, etc., etc.

Motion. Force. Illustrations of familiar forces.--Muscular force.
Force of stretched spring, etc., etc.

Consideration of some particular forces.--Gravity. Friction. Cohesion.

_Gravity._--Distinction between body’s weight and mass. Weight is the
earth’s pull upon it. Might be different while body unaltered. Centre
of gravity. Experimental determination for laminæ of various shapes.
Stable, unstable and neutral equilibrium dependent on position of
centre of gravity. Everyday illustrations. Stick balanced on finger,
etc.

_Friction._--Everyday instances. Effect if it were removed.

_Cohesion._--Three states of matter. Solids. Liquids. Gases.
Essential difference between them. Experiments showing retention of
size and shape by solids, of size by liquids, of neither by gases.

_Pressure of Liquids_--

Transmitted in all directions. Effect of boring hole in side of
vessel containing a liquid.

Pressure increases with depth.--Experiment. Lower into jar of water
cylinder closed at bottom by glass disc, the pressure of the water
supports the disc. Pour water into cylinder till bottom falls, the
lower the cylinder is sunk, the more water is required for this.

Liquids find their level.--Experiment with communicating vessels of
different sizes. Water level, spirit level. Water from reservoirs
rising to tops of houses. Exception in case of very narrow tubes.
Capillarity.

Floating power, or buoyancy of liquids.--Experiments on weight of
water displaced by bodies immersed and by floating bodies. Principle
of Archimedes.

Specific gravity.--Definition. Experimental determination (1) by
catching and weighing displaced water; (2) by loss of weight in water.

_Pressure of Air_--

Experiments showing existence of atmospheric pressure [_e.g._,
inverted jar of water, experiments with air-pump, suckers].

Barometer.--Construct by filling long tube with mercury. Show by
passing barometer tube through cork of receiver that mercury falls
when air withdrawn from above mercury in cistern, rises if air is let
in.

Action of syringes. Pumps. Construction and working of air-pump.

_Heat_--

Temperature or hotness.--Sensation not reliable guide.

Expansion.--Experiments to show in solids, liquids, gases. A few
exceptions to law of expansion, _e.g._, water near freezing-point,
ice forms on top of water. Force of expansion.

Thermometers.--Construction and graduation.

Fusion.--Temperature remains constant during fusion. Latent heat.

Evaporation and boiling.--Latent heat of vaporisation.

Boiling point depends on pressure.--Experiment of boiling water under
air-pump.

Conduction.

Convection.--Heating of water in kettle; heating of houses by hot
water.

_Sound_--

Sounding bodies always in vibration.--Bells, tuning-forks, metal
plates (vibrations shown by means of sand), strings, etc.

Mode of propagation. Illustrations. Air or other medium necessary for
transmission; no sound through vacuum.

Sounds differ in loudness, pitch, quality.

Physical cause of loudness.--Violence of vibration.

Physical cause of pitch.--Rapidity of vibration. Siren, or perforated
disc.

Strings.--Note given depends on length, thickness, tension and
material. Experiments with monochord. Illustrate by violin strings.

Harmonics.--Subdivision of strings. Experiment with riders on string.

Physical cause of “quality”.--Intermixture of other notes with
fundamental.

Resonance.--Experiments with tubes of air and tuning-forks. Organ
pipes.

Velocity of sound.--How first determined. Calculate distance of
thunderstorm.

Reflection.--Echoes.

_Work and Energy_--

Work done when force overcome or yielded to through any distance.

Gravity does work when body falls.--Work done against gravity in
lifting a body. Foot-pound, unit of work.

A body which has power to do work has “energy”.--May have in
consequence of motion, or of position, or of being heated, etc., etc.

Conservation of energy.--Transformation of energy.

THE TEACHING OF CHEMISTRY.

By CLARE DE BRERETON EVANS, D.Sc. (Lond.).

The committee appointed by the British Association in 1889 to inquire into the “Present Methods of Teaching Chemistry,” gave it as their opinion that “the high educational value of instruction in physical science has never been exhibited to its full advantage in most of our educational institutions,” and it will be admitted by the majority of those who interest themselves in the teaching of chemistry in girls’ schools that in spite of the growing tendency towards more rational methods of imparting the subject, the progress made in this direction during the last eight years has not been great enough to warrant any change in the above dictum.

After all that has been said and written about the difference between instruction and education, it should be unnecessary to reiterate that the object of our schools is not so much to develop the memories of the children as their capabilities, their powers of reasoning and doing, and although the attainment of this object is brought about chiefly no doubt by the _method_ of teaching, it is also dependent upon the subject taught.

[Elementary physical science as a basis for chemistry teaching.]

Natural science is specially valuable in calling into action at once the logical and practical faculties, training simultaneously the mind, the eye and the hand; but it is necessary in order to avoid teaching the subject dogmatically to make the course progressive--to preface lessons in chemistry, for example, by a preliminary ground-work of physics sufficient to render the chemistry intelligible. Elementary physics is the logical sequence of arithmetic, and may be taken up with the greatest advantage as soon as the four simple rules of arithmetic have been mastered; moreover the practical application of these rules afforded by simple measurements of length, area and volume is of immense use, not only because each pupil verifies for herself in this way the rules she has learnt to apply on paper, but also because arithmetic is thus shown to be of practical and not merely theoretical value. If children were taught from the beginning to make practical use of their arithmetic one of the greatest difficulties with which the science teacher has to contend later on would be obviated, that namely of explaining the application of mathematics to the solution of simple chemical and physical problems.

[Educational advantages of a progressive chemistry course.]

Chemistry again is the logical outcome of physics, and should not be attempted, because it cannot possibly be understood, until the fundamental principles of physics have been mastered. It cannot be too strongly insisted upon that chemistry should be preceded by elementary physics; the sequence, practical arithmetic, elementary physics, chemistry, being the only one which affords a satisfactory progressive scientific course suitable for being carried on throughout a school starting where the object-lessons of the kindergarten end; then by the time examination classes are reached there need be left none of those gaps in the understanding of the pupils, gaps with regard to elementary principles, which are so usual as to be looked for as a matter of course by the chemistry teacher, and which she is obliged to span here and there by dogmatic assertions on which rests as a rule all the physico-chemical knowledge required of the examination student. A well-arranged course of this kind, moreover, possesses the great advantage over others, botany or geology for example, that it may be made free from technical language, a point of considerable importance, not only because the tax upon the memories of the children is thus lightened, but because they are at liberty to express their observations in their own words. It has been truly said that “strange words are non-conductors,” and it is unreasonable to suppose that clear ideas on any subject may be imparted in a language which is only partially intelligible.

[Need for early training in science.]

It is necessary of course to begin early if a sound basis of physics is to be laid for the teaching of chemistry; the elementary physics lessons should in fact be made to continue the work of the kindergarten without any break, thus carrying out the aim of natural science teaching, which should be to foster the powers of observation and research which almost all young children possess to a very high degree; nor are these the only faculties which benefit, since physical science is specially fitted also to develop independence of thought, agility of mind and hand and soundness of judgment; the simplest experiment may be varied in a hundred ways to produce the same result, and it is this possibility of variation which gives the individual pupil so much opportunity for the exercise of originality, which cultivates quickness of observation and encourages so largely the valuable quality of self-reliance.

[“Practical” teaching.]

It is evident that a course of lectures unaccompanied by laboratory work gives no scope for the educational possibilities of technical subjects such as those with which we are dealing; the teaching must be made “practical”. It is not sufficient that the teacher should perform a number of illustrative experiments at her lectures, for it is rare to find a child capable of grasping the meaning of such illustrations; it is not even sufficient that the experiments shown by the lecturer should be repeated subsequently by the pupils themselves; this is no doubt good as far as it goes, for it breeds familiarity with apparatus and gives practice in manipulation, but that is all; as to educating the particular faculties which science is specially adapted to educate it is useless, for the results of the experiments being already known the reasoning powers are not required; on the contrary the performance of the experiment on the lecture-table has led to the belief that there is one stereotyped method of doing it, and consequently the child’s memory alone is exercised in trying to remember every detail of the apparatus used and the method of carrying it out.

For success in examinations it is now necessary to have a certain amount of practical knowledge of chemistry, and examination classes are therefore given some practical training, but this reform still remains to be extended universally to the junior classes, which need even more than the senior ones that the teaching should be objective: a child may learn and repeat correctly a dozen times that water is composed of oxygen and hydrogen, and the thirteenth time she will assure you that its constituents are oxygen and nitrogen; but let her make the gases for herself, test them and get to know them as individuals, and mistakes of this kind will become impossible.

A further reason for giving practical instruction to juniors is that examination students are generally pressed for time, being on this account often obliged to do the necessary laboratory work out of school hours; moreover they find it difficult as it is of a kind to which they are unaccustomed. It would obviously be a great advantage to train the children from the beginning in the use of apparatus during the years when such work is a recreation and a real delight to them.

[A central idea in science teaching.]

There is one other point to be noticed. The science course may be begun early and continued without intermission throughout the school career, the teaching being of a sufficiently “practical” character, but the result will not be a success unless there is a central idea running through it. From the very beginning the experiments must be chosen in illustration and explanation of the fundamental physical laws which may thus be made perfectly familiar to the pupils. It is necessary, however, that these experiments should be of the simplest character; to quote the words of the British Association report above referred to, “the lessons ought to have reference to subjects which can be readily understood by children, and illustrations should be selected from objects and operations that are familiar to them in everyday life”.

[Broad principles recommended.]

Briefly then, I would recommend that the following broad principles should be adopted with pre-examination classes:--

[(1) Elementary physical training to be made continuous with kindergarten teaching.]

(1) The course of elementary physical science which is then necessary foundation for a sound knowledge of chemistry should be made continuous with the object-lessons of the kindergarten, and should form a progressive course extending over three or four years, passing imperceptibly into elementary chemistry.

[(2) The elementary course to be entirely “practical”.]

(2) This course should be of an _entirely practical_ character and should be carried out in a room very simply equipped for the purpose. No text-books should be allowed and no notes dictated by the teacher, but each pupil should subsequently to the lesson write out in her own words an account of her own experiments, of which she is encouraged to take notes at the time of doing them.

[Advantage of occasional lectures.]

Although all formal lessons on the simple subjects of investigation serve only to prejudice the minds of the children, lectures given at rare intervals on kindred subjects and profusely illustrated serve as a healthy stimulus to the youthful appetite for experiment and research.

[(3) Choice of experiments.]

(3) The practical course should be so chosen that each experiment illustrates in the simplest possible manner some fundamental principle or “law” of nature. It is precisely here that a teacher has the opportunity of educating the logical faculties of the pupils, each of whom is required to solve independently the simple problem set before her at the lesson and is thus placed in a position to deduce for herself from her own experiment the principle involved. The children are in fact placed, as Dr. Armstrong recommends, “in the attitude of discoverers,” and it is astonishing how soon they learn to become independent in their methods of attacking new problems if their minds are not prejudiced by preconceived ideas of the results to be expected.

[(4) Size of classes.]

(4) As regards the size of the classes and the time to be allowed for each, the Committee of the British Association recommends that “a teacher should not be required to give practical instruction to more than from fifteen to twenty pupils at one time, although the classes at lectures and demonstrations might be somewhat larger”. For the course indicated below one hour a week may be made sufficient at first, but later on an hour and a half should be allowed for each practical class.

[(5) Accommodation.]

(5) As to accommodation, it is quite possible, at any rate at first, to use an ordinary class-room, but as environment no doubt does exercise a certain influence the use of a special room very simply equipped with long tables supplied with water and gas is strongly advised.[26]

[26] Full details of fittings and of the very simple and inexpensive
apparatus required are given in the syllabus issued by the
Incorporated Association of Head Masters, which can be obtained at
the “Educational Supply Association,” 42 Holborn Viaduct.

The above recommendations are meant to apply to all classes up to the time when the needs of public examinations demand a special course; this must necessarily be given by means of set lectures, as it could not otherwise be covered in the limited time which is generally allotted to the subject; they are more or less in accordance with those drawn up by Dr. Armstrong for the Committee of the British Association of which mention has been made, and which were embodied in the Syllabus of Physics and Chemistry issued by the Incorporated Association of Head Masters in 1895; since this date they have been successfully carried out in various boys’ schools. Owing to the enterprise of Miss L. E. Walter a similar course was introduced at an even earlier date into the Central Foundation School for Girls, where it is now in operation. Appended is a very brief outline of the course there pursued, together with a typical set of lessons in chemistry.

[Outline of a science course now in operation.]

On leaving the kindergarten the science teaching is confined to what is really practical arithmetic and geometry, elementary measurements being performed by the most ordinary methods. The children are thus accustomed to the use of simple apparatus such as pipettes, burettes, etc., also to the use of the balance, the simple numerical calculations involved in weighing and measuring being performed in both the English and decimal systems, which are thus made quite familiar.

The following example, quoted from Miss Walter’s paper,[27] gives a clear idea of the sort of introductory teaching needed. This lesson, although of the simplest character, had for its object to show the necessity for, and to choose a unit of length. This is how it was done: “I gave each girl but one a piece of string, all the pieces being the same length; the one odd girl I kept by me, and _we_ had a _ball_ of string. I asked the children to tell me how long their pieces were so that I could cut a similar piece. Naturally they began by guessing--a yard, half a yard; but as I had no yardstick, I feigned ignorance of what a yard was. Soon one put the string along her slate and expressed the length as a slate and three-quarters. Every one else followed suit.... After each of the sensible measurements which they made ... I did the same to my small comrade as they had done to themselves and cut off a piece of string. Then they all watched with great interest to see if my piece really did come like theirs.... This lesson may not sound very exciting, but during the whole time _each of those children was alive_, each was thoroughly interested in what she was doing.”

[27] “The Teaching of Science in Girls’ Schools,” by L. Edna Walter,
B.Sc., reprinted from _Education, Secondary and Technical_.

The preliminary course consists in its earlier stages of exercises in the measurement of length, area and volume with the use of the balance; this is followed by experiments on density, and subsequently some work on heat is done, a simple thermometer and barometer being made and graduated by each girl, who is encouraged to use them to record the weather by means of curves showing variations of temperature and pressure. It may have been completed by girls of about fourteen, who will then be quite prepared to begin chemistry, having by that time gained a very good idea of how to apply their arithmetic as well as their knowledge of the fundamental physical principles to the solution of practical problems.

It is important to point out that the system here advocated inverts the usual order of teaching chemistry. This subject is divided into “pure” and “physical,” and it is usual at the present time to begin by teaching “pure” chemistry, that is to say, the preparations and properties of a number of the commoner elements and compounds, this part being considered easier than “physical” chemistry, which however ought logically to precede it, since it treats of the fundamental laws upon which “pure” chemistry depends.

A knowledge of simple physical chemistry is now required for all chemistry examinations, candidates for which are expected to have a working acquaintance with simple physical apparatus, to be familiar with the barometer and thermometer, the effects of heat on solids, liquids and gases, density and specific heat, etc., etc.; they are liable moreover to be asked to solve any simple problems on measurement. Now by giving precedence to “physical” chemistry, all this is done and done thoroughly before examinations are thought of, so that what is generally regarded by pupils at the present time as the most difficult portion of their subject is made by this means its A B C, and the time spent upon actual examination work can be considerably curtailed.

“Pure” chemistry is introduced by the study of the methods of testing all kinds of substances so as to be able to classify them roughly as mineral or vegetable, organic or inorganic, etc. The chemistry course suggested by Dr. Armstrong and adopted by the Incorporated Association of Head Masters is strongly to be recommended, as it is drawn up particularly with a view to imparting “not only information but chiefly a knowledge of method”. It opens with “studies of the effect of heat on things in general; of their behaviour when burnt,” and goes on to the investigation of such familiar things as air and nitrogen, combustion and oxygen, hydrogen and water. Formulæ and equations are rigidly excluded, the aim being to give a broad introduction to the subject; on the other hand quantitative experiments form a much larger part of the curriculum than is usually the case, the previous training in physical methods having prepared the way for teaching chemistry in a more exact manner than is generally possible with beginners.

A girl who has gone through the scientific training outlined in the preceding pages will possess an elementary knowledge of many subjects; she will find little difficulty in mastering the information required for the London Matriculation or any other preliminary examination in physical science, the greater portion of the ground both in physics and chemistry having already been covered during the preliminary course indicated. It is certain that students who have undergone such a systematic education without hurry and without pressure, and with opportunities for reasoning out each step for themselves, will be in a condition to derive the maximum of benefit from subsequent instruction not only in chemistry but in all other branches of knowledge.

_Typical Lessons in Chemistry._

At the beginning of the lesson the problem to be solved is announced by the teacher, who invites suggestions as to how it should be attacked. A scheme of work is thus prepared which is carried into practice by the pupils; every detail of manipulation is performed by the girls themselves, who select their own apparatus, bend their own tubing, etc., referring only occasionally to the teacher for help. The scheme is elaborated as the investigation proceeds so as to form a piece of consecutive reasoning which may extend over a series of lessons.

Problem. To discover the constitution of chalk.

[Typical lesson.]

Being familiar with simple methods of testing unknown substances, heat and the action of acid are at once suggested by the pupils as a means of investigation, and a preliminary examination is made showing that heat does alter chalk in some way, whereas the addition of acid causes the liberation of a gas. The next step is to find out whether the chalk loses or gains anything by being heated; also to determine the nature of the gas given off under the influence of acid.

Suggestions are again received from the girls, who are led to decide that the first part of the question may be answered by submitting a weighed quantity of chalk to a moderately high temperature, weighing at intervals until the weight, if it changes at all, again becomes constant.