The organization of an elementary course composed largely of a progressive series of working drawings necessitates the giving of considerable attention to the selection of problems involving the use of the above-named fundamentals to make the course increasingly difficult for the student. The drawing of views involves geometrical constructions and conventions, while the dimensions, notes, and title invoke the making of arrowheads, letters, and numerals. In such an elementary course the student receives not only the training in the fundamentals, but also in their application in working drawings which furnish complete and accurate information in the desired form.
Descriptive geometry
The modern methods of teaching descriptive geometry apply the theory of the subject to applications in problems taken from engineering practice. The introduction of practical applications adds interest to the subject and makes the theory more easily understood. The number of applications should be as great as possible without interfering with the development of the theory. Such a treatment of descriptive geometry, following a thorough course in elementary drawing, should make it possible to deal with abstract principles of projection with a few well-chosen applications.
Descriptive geometry aids materially in developing the power of visualization which is so essential to the training of the engineer. The graphical applications of the subject in the solution of engineering problems may be used as a means of testing the student's ability to visualize.
There is now very little discussion relative to the advantages and disadvantages of the first and third angle projection. Since the third angle is generally used in the elementary course as well as in engineering practice, it seems logical that it should be emphasized in descriptive geometry. Recent textbooks on this subject confirm the tendency toward the use of the third angle.
The use of the third angle presents new difficulties, such as that of locating the positions of magnitudes in space in relation to their projections. Magnitudes must be located behind or below the drawing surface. To obviate such difficulties, some instructors demonstrate principles by first angle constructions. Others invert surfaces which in the first angle have their bases in the horizontal plane. This undesirable device may be overcome by using a second horizontal plane in the third angle. Such means of demonstration may be avoided altogether by considering the space relations of magnitude to one another instead of relating them to the planes of projection. This method centers the attention of the student on the relation of magnitudes represented and develops visualization. It has been found to give excellent results in both elementary drawing and descriptive geometry.
To bring the teaching of descriptive geometry into closer harmony with its application in practice, auxiliary views are frequently used instead of the method of rotations.
Briefly, then, it appears that the modern course in descriptive geometry should contain enough applications to hold the interest of the student and to test his power of visualization; that the third angle should be emphasized, and some use should be made of auxiliary views. Above all, the development of visualizing ability should be considered one of the chief aims of the course.
Methods of instruction in general courses
In teaching drawing and descriptive geometry, lectures, demonstrations, and individual instruction each have a place. Principles can best be presented in the form of lectures. The manual part of the work can be presented most effectively by means of demonstrations. The instructor should illustrate the proper use of instruments and materials by actually going through the process himself, calling attention to important points and explaining each step as he proceeds. Individual instruction given at the student's desk is a vital factor in teaching drawing, as it offers the best means of clearing up erroneous impressions and ministering to the needs of the individual student.