11. From the point of view of No. 10, compare teachers and engineers. 12. If anything will work in theory, will it work in practice? 13. From what you have learned in the chapter and from the experiments, write a paper on training in reasoning. 14. What are the main defects of the schools with reference to training children to think? 15. Make a complete outline of the chapter. REFERENCES FOR CLASS READING COLVIN and BAGLEY: _Human Behavior_, Chapters XVI and XVIII. DEWEY: _How We Think_, Parts I and III. MÜNSTERBERG: _Psychology, General and Applied_, Chapters VIII and XII; also pp. 192-195. PILLSBURY: _Essentials of Psychology_, Chapters VI and IX. PYLE: _The Outlines of Educational Psychology_, Chapter XV. TITCHENER: _A Beginner's Psychology_, Chapters V, VI, and X. CHAPTER IX INDIVIDUAL DIFFERENCES =Physical Differences.= One never sees two people whose bodies are exactly alike. They differ in height or weight or color of the skin. They differ in the color of the hair or eyes, in the shape of the head, or in such details as size and shape of the ear, size and shape of the nose, chin, mouth, teeth, feet, hands, fingers, toes, nails, etc. The anatomist tells us that we differ internally just as we do externally. While the internal structure of one person has the same general plan as that of another, there being the same number of bones, muscles, organs, etc., there are always differences in detail. We are built on the same plan, _i.e._ we are made after a common type. We vary, above and below this type or central tendency. Weight may be taken for illustration. If we should weigh the first thousand men we meet, we should find light men, heavy men, and men of medium weight. There would be few light men, few heavy men, but many men of medium weight. This fact is well shown in diagram by what is known as a curve of distribution or frequency surface, which is constructed as follows: Draw a base line A B, and on this line mark off equal distances to represent the various weights. At the left end put the number representing the lightest men and at the right the number representing the heaviest men; the other weights come in between in order. Then select a scale; we will say a millimeter in height above the base line represents one person of the weight represented on the base, and in drawing the upper part of the figure, A C B, we have but to measure up one millimeter for each person weighed, of the weight indicated below on the base. [Illustration: FIGURE V--FREQUENCY SURFACE--WEIGHT The solid line represents men, the broken line, women.]