s,
but the same difference exists in rate of development. Some children can
cover the same ground in one half or one third the time as others and do
it better. Witness the children already quoted who, skipping a grade,
were ready at the end of three years to skip again. Variability, not
uniformity, is what characterizes the abilities and rate of intellectual
growth of children in the schools, and these differences, as has already
been pointed out, are caused primarily by a difference in original
nature.

There is also great difference between the general mental make-up of
children--a difference in type. There is the child who excels in dealing
with abstract ideas. He usually has power also in dealing with the
concrete, but his chief interest is in the abstract. He is the one who
does splendid work in mathematics, formal grammar, the abstract phases
of the sciences. Then there is the child who is a thinker too, but his
best work is done when he is dealing with a concrete situation. Unusual
or involved applications of principles disturb him. So long as his work
is couched in terms of the concrete, he can succeed, but if that is
replaced by the _x, y, z_ elements, he is prone to fail. There is
another type of child--the one who has the executive ability, the child
of action. True, he thinks, too, but his forte is in control of people
and of things. He is the one who manages the athletic team, runs the
school paper, takes charge of the elections, and so on. For principles
to be grasped he must be able to put them into practice. The fourth type
is the feeling type, the child who excels in appreciative power. As has
been urged so many times before, these types have boundaries that are
hazy and ill defined; they overlap in many cases. Some children are of a
well-defined mixed type, and most children have something of each of the
four abilities characteristic of the types. Still it is true that in
looking over a class of children these types emerge, not pure, but
controlled by the dominant characteristics mentioned.

The same variation is found among any group of children if they are
tested along one line, such as memory. Some have desultory, some rote,
some logical memories; some have immediate memories, others the
permanent type. In imagery, some have principally productive
imagination, others the matter-of-fact reproductive; some deal largely
with object images that are vivid and clear-cut, others fail almost
entirely with