a. Advantages. This type of projector can be used in lighted and ventilated
rooms and permits students to take notes. The instructor can face the students while
operating the projector and thus maintain contact.
b. Materials to Use. A wide variety of techniques may be used to prepare
materials for use on the overhead projector. The instructor can point out features on the
screen by pointing to the items on the projector itself. Negative transparencies can be
easily constructed locally. These can be colored by the instructor with acetate and India
ink pens. These are inexpensive. Wide varieties of prepared transparencies are
available through service schools, training aid centers, audiovisual communication
centers, and commercial sources.
3-29. OPAQUE PROJECTOR
The opaque projector (see figure 3-3) projects material from books, magazines,
newspapers, and other printed matter on a wall or screen. Almost any color or type of
print will project on the screen.
a. Advantages. This projector is especially helpful when the instructor wants to
make a facsimile of a piece of actual equipment or map, of cardboard, heavy paper, or
on the chalkboard. The image can be projected from a picture or some other printed
material and the outline traced from the image. In order to enlarge the image, the
projector can be pushed toward the rear.
b. Disadvantages. One disadvantage of the opaque projector is that the room
has to be completely darkened. Students will be unable to take notes. The instructor
cannot observe class reactions. Another disadvantage is the quality of the projected
image. The farther rearward the projector is used, the less clear the projected image.
Figure 3-3. Opaque projector.