Contents
The three most
commonly used visual aids in most classes today are the blackboard, the overhead
projector and the 35mm slide projector. The purpose of this handout is to give
the reader some brief hints about effectively using these three resources.
The
Blackboard
Too often we
forget that the blackboard is a visual aid as slides or transparencies. It should
not simply be a scratch pad, but should be used to develop a logical flow of
information to best aid the students' understanding. Below are some suggestions
to help you use the board effectively.
- While preparing your
notes for class, briefly sketch out how the board space will be used. Keep
in mind what the main points and problems will be and how much space they
will require.
- If complicated sketches
are to be made, rough them in lightly before class to speed up later drawing
in the firm lines.
- Keep writing brief and
to the point.
- Bold block letters are
easiest to read. In a 32 ft. room, letters should be about 2" in height.
- Don't constantly face
the board. Turn frequently toward the class so that you can maintain eye contact.
- After class, walk to
the back of the room and critique your board work in terms of legibility and
organization.
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Overhead
Projection Transparencies
The overhead
projector is a simple, quick way to enhance teaching through the use of visuals.
The projector is easy to operate, having only an on-off switch and focus knob.
It requires only a little practice to master. The projector has the additional
advantage of allowing the instructor to face the students and maintain eye contact.
It also allows his/her voice to project toward the students instead of into
the blackboard. By turning the projector on and off during the presentation,
the instructor can focus the attention of the students on him/herself or the
materials. This technique also helps to add variety and change of pace to a
presentation.
There are three
basic ways of using an overhead projector, (a) as a blackboard, (b) as a demonstration
stage and (c) with prepared transparencies.
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A.
Used as a blackboard
As any instructor
knows, the blackboard is not always the ideal presentation medium. The overhead
projector can substitute for a blackboard very easily. The instructor just covers
the projection stage with some form of clear plastic such as plastic notebook
covers. He/She then writes on it with visual aid pens (water soluble type) or
wax china markers as he/she would write on the board. Regular felt tip pens
should not be used because the ink beads up instead of adhering to the plastic.
When finished with a point, the instructor can erase the writing with a damp
tissue or put on a fresh sheet to maintain a record of what was written (or
to save additional time).
B.
As a demonstration stage
One use of
the overhead can be to project such things as opaque figures or clear devices
such as rulers or protractors. And transparent liquids such as those in chemical
reactions involving color changes project well. If the instructor has a demonstration
which would be difficult for a large class to see (such as magnetic fields shown
with iron filings) the projector will show the shadow of any object which blacks
out the light.
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C.
With prepared transparencies
One advantage
of prepared transparencies is that they are set up before class, saving valuable
writing time in class. They can also help an instructor organize the presentation
more effectively since it must be worked out beforehand. We have all had the
temptation to "wing it" every now and then and those lectures are not always
of the highest quality. Prepared transparencies can be made by the three methods
described below.
- Handmade Materials:
- Clear plastic (stiff)
- Visual aid pens,
wax markers or press-on letters
- Colored transparent
adhesive
In this case the instructor simply writes on the clear plastic before class.
The colored adhesive mentioned above is available from the 3-M Company and
adheres automatically to the plastic when rubbed.
- Infra-red Materials:
- Transparency film
- Carbon-based master
- Infra-red transfer
system such as a Thermofax machine
This process is primarily for black and white materials such as charts, tables
or graphs. The master from which the transparency is made must be carbon-based
print such as pencil, Xerox, or India ink. Often the most reliable way to
produce a master is to draw it first and then make a Xeroxed copy to be used
in producing the transparency.
Once the master
is made, the transparency film is placed over the master with the notch in
the upper right corner. These two sheets are fed into the Thermofax according
to the machine's specifications. When they emerge, the transparency will burn
black wherever the master was black. It can then be peeled off the master
and mounted (if desired). If color is desired, the transparency can then be
colored with visual aid pens. (This same procedure can be used to make 2x2
slides if the master is small enough.) The films used in ths process come
in several colors and styles. Varying the color with the concepts being presented
can help to lend coherence and interest to many subjects.
- Xerox Materials:
- Xerox brand transparencies
- Master of any kind
(that can be copied by a Xerox machine)
- Any late model Xerox
machine
This process works on the electrostatic principle which is the basis for
all Xeroxing. The film is placed in the machine where the paper usually
resides (according to the manufacturer's specifications). The rest of the
process is identical to any copying. Color can be added as in the infrared
process.
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General
Suggestions
- Don't attempt to put
too much information on a transparency. Crowded tables or illustrations will
be too difficult to read. Twenty to fifty words or 24 to 30 pieces of data
are sufficient. The exception is when the instructor has made a transparency
from a worksheet which all the students have. The transparency is then used
to direct the students' attention on their own copies.
- Use large, plain letters
and few words. Primary type of any letters approximately 1/4" to 1/2" in height
will project well in a normal classroom. Use the following guide to help determine
what would be easily seen in your room.
|
Viewing
Distance
|
Minimum
Type Size
|
|
128
feet
|
4
inches
|
|
64
feet
|
2
inches
|
|
32
feet
|
1
inch
|
|
16
feet
|
1/2
inch
|
|
8
feet
|
1/4
inch
|
Lines should be spaced at a ratio of 1.5/1 with the letter height.
- Leave a border around
the body of the material for easier viewing.
- Use color to enhance
points or tie together common concepts.
- Use overlays to sequentially
develop a concept.
- Most data can be more
quickly grasped in graph form than in tabular form. They are also more visually
interesting and easily remembered.
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35MM
Slides
Legibility
is the prime requirement for slides; if the audience can't read/see the material
clearly, the slide doesn't accomplish the desired communication.
- Avoid large tables of
data on slides. If the slide contains a lot of data, none of it can really
be deciphered, and the chances are that you really want to talk about only
part of it, anyway. Reduce the data to the essential data using rounded figures;
or plot the data and present the graph; or use more than one slide. Several
simple slides are better than one complicated slide.
- Illustrations in textbooks
are generally rather detailed, and copying them on slides often results in
a less-than-satisfactory projection. It is frequently better to redraw the
illustration, using wider line widths, fewer and simpler captions, and larger
lettering. Color can also be used to highlight details, boundaries of regions
on the drawing, etc.
- Keep graphs simple and
be sparing in the use of captions.
- The standard 35mm slide
is about 24 x 36mm, but when mounted in a slide mount the actual projection
frame is about 15/16" 1-3/8". It is better to use all your slides in horizontal
format, that is, the projected picture is wider than it is high. If the projector
lens-projector-distance-screen size combination is such that a horizontal-format
slide fills the screen from side to side, then a vertical-format slide will
spill off the top and bottom of the screen unless the screen is square (most
projection screens are wider than they are high). Sometimes, of course, one
is obligated to use vertical-format slides, but it is preferable to stick
to horizontal format if possible.
- Letter size is very important.
On artwork, never use any letter or symbol smaller in height than 1/25 of
the height of the layout. Letters are easier to read if they are 1/15 the
height of the slide, or larger. As
an example, suppose you are typing material for a slide using an IBM Selectric
typewriter with a Letter Gothic (Sans serif) 12-pitch type ball. You will
use only the capital letters, which are just under 1/8-inch high, and the
size of the copy you plan to photograph is 6" x 9". If you will use a 9' x
9' projection screen to display this slide, filling the screen from side to
side, the projected letters will be 1.6 inches high (actually a bit less,
because the letters on the type ball are a little less than 1/8" high). Letters
1.6 inches high can be seen about 50 feet. The lettering could be easily read
in an ordinary classroom, but if you are trying to communicate with 500 people
in an auditorium, the people in the back third of the room will be cursing
your name. If the screen is smaller than 9' x 9', which often is the case,
the number of your fans in the audience will decrease proportionally.
- Limit each slide to one
main idea.
- Color slides are more
effective, easier to make, and cheaper when you consider darkroom time. Color
film can also be used for black and white slides, so you need to use only
one kind of film.
- Use light colors when
making slides. The human eye is most sensitive to yellow. Other easily perceived
colors include orange, pink, light blue and light green. Avoid dark blue and
dark red.
- Dark-colored backgrounds
are better than either black or white.
- If you plan to use the
same slide at several different points in your presentation, use duplicate
slides. It isn't good practice to have the projectionist re-show a single
slide.
- Don't leave a slide on
the screen after you've discussed it. Insert a "blind" slide, or turn the
projector off.
- Use a projector with
a remote control so you can operate the show. If such equipment is unavailable,
arrange some silent signal with the projectionist.
- Don't plan a presentation
around slides you happen to have already; plan a presentation to say what
you have to say, and then arrange the slide show, shooting new slides if necessary.
- Though the room must
be fairly dark while slides are being used, don't make it so dark that the
students cannot see to write down notes (if possible).
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Slide
Production
TITLE SLIDES:
Title slides can be made
in the same manner as transparencies by dividing a sheet of paper into small
slide-sized squares (2"x2") and typing or printing single words or short phrases
in each square. (Remember that the actual projection frame, which is the size
of the hole in the slide mount, is 15/16" x 1-3/8". Therefore the printed message
should be centered in this space.) Running this sheet plus a piece of heat-sensitive
film through the Thermofax (or equivalent) produces a sheet of twenty slides
which can be cut up and mounted in frames.
It is also possible to type
directly on 3M transparency film or on student report covers to make slides
in the same manner discussed above. Caution must be exercised, however, since
the ink will rub off. It is best to spray the completed sheet with artists'
fixative.
In both instances, be sure
to use a large enough type size.
PHOTOGRAPHIC
SLIDES:
Using color slide film such
as Kodak's Ektachrome X will produce bright colors as well as good black and
white slides. Kodachrome film makes quite acceptable slides, but processing
requires several days as the exposed film must be sent away for development.
Ektachrome film can be processed overnight (or in just a few hours) at most
film laboratories in Austin.
Color can be added to plain
slides by using tinted acetate (such as report covers or 3M colored film). It
can also be added by painting on the film with transparent paint such as that
made by Parlab or with pens made for writing on transparencies.
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Films
The most important aspect
in the use of films for instructional purpose is the necessity of careful planning.
The instructor must select the film thoughtfully, considering exactly how it
will enhance the students' understanding of the material being studied. In addition,
the instructor must be thoroughly prepared to use it. The following utilization
pattern may assist you in your planning:
- Determine your purpose
for using the film.
- To prepare students
for the next unit of study.
- To demonstrate examples
for the concepts they have just learned.
- To demonstrate skills
to be learned.
- To stimulate discussion.
- Etc.
- Prepare yourself to show
it by becoming thoroughly acquainted with its content.
- View the film, taking
notes as you go.
- Read the film guide;
check its sample discussion questions.
- Plan activities and,
if needed, develop a quiz covering the film content.
- Make necessary arrangements
so the film will be available at the proper time.
- Arrange for a projector
and screen if your classroom is not permanently equipped with them.
- Arrange for a projectionist
to handle the showing or be ready to handle it yourself.
- Help your students be
ready to view the film and to profit from it.
- Make it clear to the
students why they are seeing the film and what they are expected to learn
from it.
- Plan appropriate ways
to involve your students actively in learning from it.
- Discuss what is already
known about the subject of the film and lead into what might be expected
from its showing.
- Introduce key words
by listing them on the board. Develop class familiarity with them by explaining
their meanings in the context of the film to be shown.
- Develop a list of
questions to be at least partially answered by the information contained
in the film. List these questions on the board (or in a handout) as a
guide to viewing.
- Plan student activities
as follow-ups to the showing.
- Divide the class
into small groups after the presentation of an "open end" film (one which
presents a problem but does not provide a solution). Ask each group to
propose a solution to the problem. Re-group to compare results and, perhaps
to produce a consensus.
- Take a field trip
for which the film was used as preparation.
- Practice skills taught
in the film.
- Administer a written
or oral check test covering major points treated in the film.
- Ask the class to
obtain more detailed information about main ideas in the film.
Information on obtaining
films to use in instruction at UT may be obtained from:
Gary Lay
Audio Visual Library
Undergraduate Library, FAC 101
495-4467
NOTE: Whatever you do, DO
NOT use a film as a "baby-sitting" device (e.g., used only to "make" a class
session when you are out of town!). The students will resent your wasting their
time.
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ADVANTAGES
AND DISADVANTAGES OF SELECTED FORMS OF MEDIA
BLACKBOARDS
Advantages
- Accessible and relatively
simple to use.
- No special equipment
(except chalk) needed.
- Inexpensive.
Disadvantages
- Takes practice to be
able to write and draw well on the board.
- Cannot be used to show
intricate, detailed drawings.
- Tendency to talk to the
board while writing. 4. Difficult to show color in drawings.
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OVERHEAD
PROJECTORS
Advantages
- Simple to use.
- Supplies are inexpensive.
- Can show color and graphics
well.
- Can be used as a blackboard,
demonstration stage, or with prepared materials.
- Instructor faces class
while writing.
- Helps organize lectures.
- Can be used with lights
on!
Disadvantages
- Every room on campus
is not equipped with one.
- Bulbs may burn out.
- Takes some time to prepare
transparencies.
- You must provide time
for students to copy what is on the transparency or provide the content of
the transparency on a handout.
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SLIDES
Advantages
- Relatively simple to
use.
- Supplies are not too
expensive.
- Can show color and graphics
very well.
- Helps organize lecture.
- Slide-tape presentations
can be developed.
- In some rooms there is
a technician who will set up the projector for you.
Disadvantages
- Every room on campus
is not equipped with one.
- Bulbs may burn out.
- Takes time to prepare
the slides (take pictures, and have them developed).
- Room has to be quite
dark when showing slides; making notetaking difficult.
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FILMS
Advantages
- Can show movement.
- Can show colors clearly.
- Can present concepts
of abstract ideas.
- Can be used to "re-live"
the past.
- Can be used to stimulate
discussion.
- Can be used to introduce
or conclude a unit of study.
Disadvantages
- Takes a great deal of
time to order and preview.
- Can be expensive.
- If ordered, it must arrive
at the right time.
- Must have equipment and
someone to run it.
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VIDEOTAPES
Advantages
- Can present movement,
color changes, etc.
- Can present documentaries,
plays, etc. from TV which relate to the course.
- You can make them yourself.
- Can be produced especially
for your class.
- Can be shown many times
(to whole class or individually).
- Can be used to provide
feedback to students on their progress in skill courses.
- Makes excellent use of
many different kinds of non-verbal communication.
Disadvantages
- Must have equipment for
making and viewing tapes.
- Purchasing ready-made
tapes can be expensive.
- Takes quite a bit of
time to produce your own tapes.
- Students are not used
to viewing TV critically and may not take it seriously at first.
- Not suited for the presentation
of large amounts of specific facts and data.
- Moves at a steady pace
with no time for assimilation of information and concepts presented.
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General
References
Brown, J.W., Lewis, R.B.,
and Harcleroad, F.F. (1973). AV Instruction: Technology, Media and Methods.
New York: McGraw-Hill Book Company.
Nicholas, D.J., Crow, J.A.
(1974). Instructional Technology: Basic Skills. Austin: University Stores,
Inc.
Ohliger, J. and Gueulette,
D. (1975). Media and Adult Learning: A Bibliography with Abstracts, Annotations
and Quotations. New York: Garland Publishing, Inc.
Additional references and
periodicals such as Audiovisual Instruction are located in the Education-Psychology
section of the Perry-Castaneda Library (PCL).
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October 3, 2002
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