Suppose we breathe air that contains too little oxygen, what
will be the effect on the corpuscles?

What will be the effect on oxidization in the tissues?

And what is the effect of poor oxidization on physical
vitality?

On mental vitality?

The class that answered these questions not only had the information
belonging to each separate question, but also understood the lesson as
a whole, because each question grew out of the ones that preceded it,
thus making the recitation a unified whole.


5. _The principle of clearness_

Questions must be made clear, so that their meaning may be understood.
This is not always an easy task, and the teacher frequently misses
being wholly clear. This is evidenced by the fact that often when a
pupil fails to answer a question asked in one way, he can answer it
easily when the wording is changed. This means that the difficulty for
the pupil existed in the question, and not in the answer.

Clearness in questioning involves three factors: (1) Freedom from
ambiguity or obscurity of wording; (2) adaptation to the age and
understanding of the pupil; (3) reasonable brevity.

_a. Freedom from ambiguity or obscurity of wording._--This is