The mind has what may be called three different levels. The first is
the _sensory_ level, represented by the phrase "in at one ear and out
of the other." Every one has experienced reading a page when the mind
would wander and only the eyes follow the lines on down to the bottom
of the page, nothing remaining as to the meaning of the text. It is
easy to glance a lesson over just before reciting, and have it stick
in the memory only long enough to serve the purposes of the
recitation. Things learned in this way are not permanently serviceable
and really constitute no part of an education.

The second level of the mind may be called the _memory_ level. Matter
which enters the mind only to this depth may be retained for a
considerable time but is little understood and hence of small value.
All rules and definitions committed without knowing their meaning or
seeing their application, and all lessons learned merely to recite
without a reasonable grasp of their meaning, sink only as deep as the
memory level.

The third and deepest level is that of the _understanding_. Matter
which permeates down through the sensory and memory levels, getting
thoroughly into the understanding level, is not only remembered but is
understood and applied, and therefore becomes of real service in our
education. Of course it is clear that the ideal in teaching should be
to lead our pupils so to learn that most of what enters their memory
shall also be mastered by their understanding.

Therefore, in the recitation we should test not alone to see what the
pupil knows, but also to see _how he knows it_; not only to find out
whether he can recite, but also what are his methods of learning. We