Another important issue is the use of straight edges. Students feel a tremendous need to produce that 'perfect' line. It is the opinion of this author that when you start using a straight edge, it is no longer a true sketch and you have lost much of the speed and flexibility advantage of sketching.

For those who would like to incorporate more hands-on techniques to help develop their student's visualization techniques while they work on their sketches, material in Chapter 5, Visualization for Design, can be incorporated. For those who would like more formal theory on projection introduced at this point, material from Chapter 8, Multiview Drawings, and Chapter 9, Pictorial Drawings, can be incorporated.

Besides teaching students the applied skills of the different types of projections, make sure they understand how all these different types of projections relate to each other (see Table 1 in Chapter 8). Two of the more important divisions are between parallel and perspective projection and between multiview and pictorial sketches. Use example sketches such as those in Figure 4.26 to point out the differences.

This is also a good opportunity to talk about the importance of object orientation to the projection plane. Sketch an object with a majority if its features parallel to the projection plane and then oriented skew to it. Let them experience how much harder it is to draw the details properly.

As with oblique pictorials, the choice of a front view orientation is an important first step. Using a physical object, show students various ways of orienting the object and ask them to tell you the pluses and minuses of each orientation.

Again with a physical object, show how various principal views can be generated from an object. Though rotating the object is often more intuitive to the student, also use an 'image plane' made from clear plastic (or just a transparency in a frame) rotated about the object to show how the equivalent views can be generated. There are a number of techniques presented as exercises in Chapters 8 and 9.

With two-view sketches you can introduce the concept of adjacent views and view alignment (see also Section 8.4). Encourage your students to use construction lines to project overall dimensions and feature locations between the views. Identify which dimensions are being represented in each of the views and which dimension is being shared.

Once three-view multiviews are introduced you have the opportunity to go back and tie together some of the basics of projection theory and the relationship between pictorials and multiviews. One in-class exercise you can do is to associate each projection plane with each view name (e.g. the horizontal projection plane is associated with the top view). In addition, you can have them identify which two views share the same dimension. You can also display the same object as an isometric pictorial and a multiview and compare how the dimensional axes are laid out in each of these representations.

You can also compare the construction of an object in one-point perspective sketch and as an oblique pictorial. Here you can clearly point out the lack of convergence of the depth dimension.

Emphasize that guide lines (construction lines) are just as important in lettering as they are in sketching and drafting. You may decide, however, that those students who don't seem to be having too much trouble keeping their lettering aligned vertically, can skip putting in their vertical guidelines.

Cover not only the design style of each of the letters but also the numbers. There especially is a tendency to use non-standard designs for numbers among beginning students. Proper spacing is also something important to cover. Emphasize that the idea is to have uniform volume between the letters, not necessarily uniform distances between the nearest elements of the letters.

If you can, point out examples of graphics which would clarified with the addition of a small amount of text and text notes which would be clarified by the addition of some graphic elements.