An overhead transparency is an image usually 8 ½” * 11” on clear acetate or plastic which has been prepared
For use on an overhead projector. An overhead projector is a device which throws an image on a screen. It is placed
In front of an audience and may be used in a completely lighted on semi-darkened room: it utilized 3 ¼” x 4”,
7” x 7”, 10 * x 10”, or most commonly, 8 ½” x 11” transparencies.
The lens system of the overhead projector is designed so that the projector can be placed in the front of a room.
The projection angle often causes the image to appear in a trapezoid form sometimes called “keystoning” (see illustration).
This is corrected by tilting the screen as shown in the accompanying figures. This distortion is not always bother some and
does not measurably change the amount of light on the screen. The projector should be placed as low as possible,
As illustrated, so that the body of the equipment does not interfere with the line of vision between the students and the
The overhead transparency and projector have become extremely popular since the early 1960’s. the cost of the
projector has decreased, and the potential for local production of transparencies has increased. In some instructional
settings the overhead projector makes an excellent replacement for the chalkboard. There are many advantages to this
simple projector and its associated materials.
- The equipment is used in the front of the room. The teacher can maintain eye contact with the class while
Using the equipment.
- A bright image can be projected in a fully room. This permits the teacher and learns to see each other.
- Materials to be used on the overhead projector are easily produced by the teacher in the local school. The
teacher in the local school. The teacher may write on a piece of acetate during the class as he would
use the chalk board.
He may use transparencies which have been produced through heat or chemical processes. In either case
The transparency is a highly accessible and easily used medium of instruction.
- The equipment is simple to operate and has no maintenance problems save the occasional replacement of the lamp.
In their enthusiasm for use of the overhead projector, teacher often overlook some of the limitations.
- Unless the equipment is properly positioned the base and head of the projector may obstruct the students line of
Sight. The projector should never be placed on the teacher’s desk in the front of the room. A low projector stand
Or a table with a recessed out-out is essential.
- Since the overhead projector becomes such a vital part of the teaching – learning process, it cannot easily be
scheduled for use in one classroom one hour and in another the next. There fore it may be necessary to assign
an overhead projector to each room if teachers have extensive needs for this piece of equipment. This may
create an economic burden.
Programmed instruction is the use of programmed materials (or a program) to achieve educational objectives.
Some programs are designed for devices which are commonly referred to as teaching machines. A teaching machine is
a device that presents a program. Most machines control the material to which the student has access at any moment,
preventing him from looking ahead or reviewing old items. Many machines contain a response mechanism: a tape
on which the student writes, a keyboard, or selection buttons, some provision is made for knowledge of results, either
by revealing the correct answer after the individual responds or by advancing to the next item, thereby signaling
correct completion of the previous item. However, most programs are in the form of programmed texts. These
texts do not different in outward appearance from conventional workbooks or texts; no equipment is required to use
a programmed text.
In programmed instruction information is presented; the presentation is controlled, usually by small steps;
The presentation stimulus demands and active response by the learner; the student is either told whether his response
is correct, or he is permitted to judge whether his response is correct as he compares his with the one given in the program;
and there is no established pace at which the learner must move.
Some of the advantages of programmed learning are inherent in the characteristics of the medium, i.e., the
Individual can move at his own pace; the individual must respond to the stimulus (there is little opportunity for inactivity);
And the individual knows immediately whether he is right or wrong. Other advantages include the following:
- Student follows a logical sequence of thought.
- By the time the programmed instruction reaches the learner, it has usually been field tested and verified, thus ensuring optimum learning and optimum use of student time.
- Programmed instruction is especially well-suited to many kinds of learning tasks.
- A wide variety of media can be employed in presenting stimuli; audiotapes, films, slides, filmstrips, flat pictures, etc.
- Programmed instruction usually works best with the cognitive learning objectives – those dealing with factual
and skill learning. Many teachers question the success of programmed learning since it tends to emphasize
content and does not permit feelings or emotions to be used.
- Some programs, especially those which are organized in a linear fashion, tend to be somewhat dull, especially
for brighter students.
- Programs are difficult to prepare on a local basis. They are time-consuming to write and to field test.
If commercial programs are not available, and locally prepared programs cannot be written, the use of PI
is not possible.