5. In what other way it might be made to happen. In chemistry almost
every substance can be prepared in several different ways. The common
method is in most cases made so by some consideration of convenience,
cheapness, or safety. Often only one method is considered in one place
in a text book. In a review, however, several methods can be associated
together. Tests, uses, etc., will vary, too, and should be studied with
that fact in view. In physics phenomena illustrating a given principle
can usually be made to take place in several different ways. Often very
simple apparatus will do to illustrate some fact for which complex and
costly apparatus would be convenient. In such case the study of the
experiment with that fact in view becomes important to us who need to
simplify apparatus as much as possible.
6. Special precautions which may be necessary. Some experiments always
work well, even in the hands of those not used to the work. Others are
successful--sometimes safe, even--only when the greatest care is taken.
Substances are used constantly in work in chemistry which are deadly
poisons, others which are gaseous and will pass through the smallest
holes. In physics the experiments usually present fewer difficulties of
this sort. But special care is necessary to complete success here.
7. Other things shown by the experiment. While the main object should
be kept in most prominent view in all experimental work, the fullest
educational value will come only when all that can be learned by the use
of an experiment is carefully considered.
In selecting just the work to be taken up with a given class of
children, attention must be paid to the selection of the appropriate
matter to be presented and the well adapted method of presenting it. The
following points should be carefully considered:
1. The matter must be adapted to the capacity of the child. This must be
true both as regards the quality and the quantity. The tendency will be
to teach too much when the matter presented is entirely new, but too
little in many cases where the pupil already knows the subject in a
general way. Matter is valuable only when given slowly enough to permit
of its being fully understood and memorized, while on the other hand
method is valuable only when it secures the development of attention and
the various faculties of the child's mind by presenting a sufficient
amount of the new.
2. The work must be based on what is already known. This, one of the
best known of the principles of teaching, is of at least as great
importance in physical science as in any other department of knowledge.
It seems to me in many cases to be more important here than elsewhere.
It is not necessary to reach each point by passing over every other
point usually considered. Lessons in electricity or sound, for instance,
can be given to children who have done nothing with other parts of
science. But a natural beginning must be made, and an orderly sequence
of lessons adopted. Children will not do what adults would find almost
impossible in covering gaps between lessons.
Science may be compared to a great temple. Pillars, each built of many
curiously joined stones, standing at the very entrance, represent the
departments of science so far as man has studied them. We need not dig
down and study the foundations with the children; we need not study
every pillar nor choose any particular one rather than some other; but
we must learn something of every stone--of each great fact--in the
pillar we select, be it ever so little. The original investigator climbs
to stones never before reached, or boldly ventures away into the dim
recesses beyond the entrance to bring back hints of what may be known
and believed a hundred years hence, perhaps. The exact investigator
measures each stone. Patiently and toilsomely scientific men examine
them with glass and reagent. We need not do this, but we must omit none
of the stones.
3. The work must be continuous. To continue the figure, the stones must
be considered in some regular order. One lesson in electricity, one in
sound, then one in some other department is injurious. We remember best
by associated facts, and, while with the child this is less so than with
the man, one great object of this work is to teach him to remember in
that way.
4. Experiments should never be performed for mere show. Of two
experiments which illustrate a fact equally well it is often best to
select the most striking and brilliant one. The attention and interest
of the child will be gained in this way when they would not be to so
great an extent in any other. The point of the experiment, however,
should never be lost sight of in attention to the merely wonderful in
it.
With older pupils, and especially with those who use books for
themselves and perform the experiments there considered, the fact that
experiments demand work, downright hard work, with care, and patience,
and perseverance, and courage, cannot be kept too prominently before
them.
5. Every lesson should have a definite object. Not the general value of
the experiment, but some _one thing_ which it shows should be the object
considered.
6. Each experiment should be associated with some truth expressed in
words. The experiment should be remembered in connection with a definite
statement in each case. The memory of either the experiment, or the
principle apart from the experiment, is a species of half knowledge
which should be avoided. An unillustrated principle must, when the
necessity arises, be stored in the memory; and in the systematic study
of books this necessity will often come. But we should never crowd this
abstract work on the memory unassisted by the suggestive concrete, when
the concrete aid is possible.
7. All that is taught should be true. It is not necessary to attempt to
exhaust a subject, nor to attempt to teach minute details regarding it
to the pupils in our schools, but it is necessary that every statement
given to the pupil to be learned and remembered should contain no
element of falsehood.
The student in mathematics experiences a feeling of growing strength and
power when he finds, in algebra, that the formula he used in arithmetic
in extracting a square root has grown in importance by leading
indirectly to a theorem of which it is only one particular case--a
theorem with a more definite proof, and a larger capability for use than
he had thought possible. When he finds a still simpler proof for the
binomial theorem in his study of the calculus, his feeling of increasing
power and the desire for still greater results deepens and intensifies.
Were he to find, on the contrary, that from a false notion of the means
to be used in making a thing simple, his teacher in arithmetic had
taught him what is false, we should approve his feeling of disgust and
disappointment. Early impressions are the most lasting, and the hardest
part of school work for the teacher is the unteaching of false ideas,
and the correcting of imperfectly formed and partially understood ideas.
I took a case from mathematics, the exact science, to illustrate this
point. But I must not neglect to notice the difference between that
subject and physical science. The latter consists of theories,
hypotheses, and so-called laws, supported by _observed facts_. The facts
remain, but time has overthrown many of the hypotheses and theories, and
it will doubtless overthrow more and give us something better and truer
in their place. While a careful distinction between what is known and
what is believed is necessary, I should always class the teaching of
accepted theories and hypotheses with the teaching of the true.
But teachers, with more of imagination than good sense, teach
distinctions which do not exist, generalizations which do not
generalize, and do incalculable mischief by so doing.
8. Experimental work should be thoroughly honest as to conditions and
results. If an experiment is not the success you expected it would be,
say so honestly, and if you know why, explain it. The pupil should be
taught to know just what _is_, theory or expectation to the contrary
notwithstanding. Discoveries in physical science have often originated
in a search for the reason for some unexpected thing.
The relation of the study of science to books on science should be
considered. For the work done with pupils before they are given books to
use for themselves, any attempt to follow a text book is to be deplored.
The study of the properties of matter, for instance, would be a fearful
and wonderful thing to set a class of little ones at as a beginning in
scientific work. Just what matter, and force, and molecules, and atoms
are may be well enough for the student who is old enough to begin to use
a book, but they would be but dry husks to a younger child. Many of the
careful classifications and analyses of topics in text books had far
better be used as summaries than in any other way; and a definition is
better when the pupil knows it is true than when he is about to find out
whether it is or not.
An ideal course in science would be one in which nothing should be
learned but that found out by the observation of the pupil himself under
the guidance of the teacher, necessary terms being given, but only when
the thing to be named had been considered, and the mind demanded the
term because of a felt need. Practically such a method is impossible in
its fullest sense, but a closer approach to it will be an advantage.
Among the numerous good results which will follow the study of physical
science are the following:
1. The cultivation of all the faculties of the child in a natural order,
thus making him grow into a ready, quick, and observing man. Education
in schools is too often shaped so as to repress instead of cultivate the
instinctive desire for the _knowledge of things_ which is found in every
child.
2. The mechanical skill which comes from the preparation and use of
apparatus.