2. Associated facts would be learned in studying in this way which would remain unknown otherwise.

But all the advantages would be associated with disadvantages too. Long periods of time would have to be given for comparatively small results. The history of science is full of instances in which years were spent in the elaboration of some law, or principle, or theory which the school boy of to-day learns in an hour and recites in a breath. Why does water rise in a pump? Do all bodies, large and small, fall equally fast? The principles which answer and explain such questions can be made so clear and evident to the mind of a pupil that he would almost fancy they must have been known from the first instead of having waited for the hard, earnest labor of intellectual giants. And science has gone on, and for us and for our pupils would still go on, only as accompanied with numerous mistakes and disappointments.

What method shall we adopt in the teaching of science? It must differ according to the age and capacity of the pupils. An excellent modification of the method of original investigation may be arranged as follows:

The children are put in possession of all facts relating to conditions, the teacher explaining them as much as may be necessary. The experiment is performed, the pupils being required to observe exactly what takes place, the experiments selected being of such a nature that any previous judgment as to what ought to occur is as nearly impossible as may be. We predict from knowledge, real or supposed, of facts which are associated in our minds with any new subject under consideration. Children often know in a general, vague, and indefinite way that which, for the sake of a full and systematic knowledge, we may desire them to study. What they know will unconsciously modify their expectations, and their expectations in turn may modify their observations. We are apt to believe that happens which we expect will happen. There ought to be no difficulty, however, in finding simple and appropriate experiments with which the child is entirely unacquainted, and in which anything beyond the wildest guess work is, for him, impossible. The principal use which can be made of this method is in the mere observation of what takes place. Nothing which the child notices correctly need be rejected, no matter how far removed from the chief event on the object of the experiment. Care that the pupil shall see all, and separate the essential from the accidental, is all that is necessary.

But the original investigator assigns reasons, and with care the children may be allowed to attempt that. This, however, should not be carried far; incorrect explanations should be criticised; and the class should at length be given all the elements of the correct explanation which they have not determined for themselves. Later, pupils should be encouraged to name related phenomena, to mention things which they have seen happen which are due to associated causes, and to suggest variations for the experiment and tests for its explanation. Good results may be made to follow this kind of work even with very young pupils. A child grows in mental strength by using the powers he has, and mistakes seen to be such are not only steps toward a correct view of the subject under consideration, but are steps toward that habit of mind which spontaneously presents correct views at once in study which comes later in life.

Another method is this: The pupil may know what is expected to happen, as well as the conditions given, and held responsible for an observation of what does happen and a comparison of what he really observes with what he expects to observe. Explanations are usually given a class, often in books with which they are furnished, instead of being drawn from them, in whole or in part, by questioning, when physical science is studied in this way. Indeed, this method is a necessity when text books are used, unless experiments from some outside source are introduced.

Who shall perform the experiments? With young pupils everywhere, and in most of our common, and even in many of our graded schools, the experiments must be performed by the teacher. With young pupils the time is too limited, and the responsibility and necessary care too great to permit of any other plan being practical. In many of our schools the small supply of apparatus renders this necessary even with larger pupils. Added to the reasons already given is the important one that in no other way--by no other plan--can the teacher be as readily sure that his pupils observe and reason fully for themselves. In this normal school a course in physics, in which the experiments are all performed in the class room by the teacher, is followed by a course in chemistry, in which the members of the class perform the experiments for themselves in the laboratory. And, notwithstanding the age, maturity, and previous observation of the pupils, a great deal must be done both in the laboratory and in the recitation room to be sure that all that happens is seen--that the purpose is clearly held in the mind--that the reason is fully understood.

With older pupils and greater facilities, however, the experiments should be performed by the pupils themselves. Constant watchfulness is necessary, it is true, to insure to the pupil the full educational value of the experiment. With this watchfulness it can be done, and the advantages are numerous. Among them are:

1. The learning of the use and care of apparatus.

2. The learning of methods of actual construction, from materials at hand, of some of the simpler kinds of apparatus.

3. The learning of the importance of careful preparation. An experiment may be performed in a few minutes before a class which has taken an hour or more of time in its preparation. The pupil fully appreciates its importance, and is in the best condition to remember it only when he has had a part of the hard work attending that preparation. Again, conditions under which an experiment is successfully performed are often not appreciated when merely stated in words. "To prepare hydrogen gas, pass a thistle tube and a delivery tube through a cork which fit tightly in the neck of a bottle," etc., is simple enough. Let a pupil try with a cork which does not fit tightly and he will never forget that condition.