Suppose it is a question of having the pupil grasp the idea of the sphericity of the earth.
"How We Think"
John Dewey
This is different from teaching him its sphericity as a fact.
"How We Think"
John Dewey
But he has not thereby acquired any idea of the earth's sphericity; at most, he has had a certain image of a sphere and has finally managed to image the earth after the analogy of his ball image.
"How We Think"
John Dewey