unique, but will be largely determined by three factors; the aptitudes
of the teacher, himself, the group that he is teaching, and lastly,
the consideration of the individual pupil. Ability to adapt ones
procedure so as to most nearly meet these requirements, will come
about only through experience. Ability to profit by experience, the
human attribute which makes possible the progress of civilization, is
a no less valuable asset to a teacher than to any other member of
society.

Balliet points out that science teaching has passed through three
stages in the past generation. The first stage is characterized by the
textbook method, occasionally supplemented by illustrative experiment,
performed by the teacher. The second stage is characterized by
individual laboratory experiment, a manual for a guide, and by a lack
of application of the principles except for a few traditional cases.
The third stage improves upon the second by leading the pupil, after
formulating his generalizations, to apply them to the facts and
phenomena of nature. "But", continues Balliet, "we must advance to a
fourth stage. We must not only apply the generalizations, but make the
_explanation_ of the facts and phenomena of nature--the interpretation
of nature--the very goal of science teaching." All problems should be
chosen then in the light of this last aim. The problems must be
natural, not in any way artificial, and they should be those of the
immediate environment of the pupil. To meet these obligations may be
in some cases difficult, but it should not be impossible.

In biological science there is a rich field permitting a considerable
choice in method. There are observations, projects, experiments,
excursions, individual reports, book readings, quizzes, and
conferences. In a single well chosen problem or project nearly all of
these will be employed. Biology lends itself ideally to the problem
method of teaching. By using some every day problem of the pupil, his
interest is assured. Even a seemingly simple problem if skilfully
directed, will ramify into several fields of biology before its
solution is completed. And the number of practicable problems is
almost limitless, but not all are equally good for the purpose, so the
teacher must often tactfully modify the pupils choice. Original
choices are likely to be too complex for the pupil to solve at his
stage of progress, so must be simplified, without his feeling that he
has been interfered w