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.
4. The learning of the importance of following directions. Chemistry,
especially, is full of those cases where this means everything.
Sometimes, not often in experiments performed in school, however, it may
mean even life or death.
The time for experiments should be carefully considered. When performed
by the teacher they should be taken up during the recitation:
1. If used as a foundation to build upon, at the beginning of the
lesson.