Historically,
instructors could have any color of chalkboard they wanted as long as
it was black. Today the chalkboard comes in all colors, shapes, sizes
and degrees of portability. Some have special surfaces that require a
particular type of felt-tip pen rather than chalk. Most times, however,
this medium includes a large writing area, a writing substance (usually
chalk), and an eraser.
The chalkboard is so common that not much attention is paid to maximizing the use of this
fantastic
sub-strategy, but by following the guidelines below, the potential of
even the trusty old "blackboard" can be greatly increased.
Advantages or Special Purposes
1. Availability. Most areas assigned for instruction are equipped with chalkboards. Also, if more board space is needed, portable boards of various types and styles are handy.
2. The chalkboard is inexpensive, especially when the usable life of the board is considered.
3. It is flexible in use in the sense that instructors may use it, learners may use it and changes can be easily made through erasure.
4. Space. Lots of writing space is usually provided.
5. The chalkboard can be used to present more formally prepared lessons, or for informal, spontaneous sessions.
Disadvantages or Limitations
1. The chalkboard carries with it a "temporariness." Material put on the board cannot be saved or made permanent.
2. Chalkboards are often fixed in such a way that they are not always at a comfortable height for all potential users.
3. Being fixed, chalkboards can put restrictions on the use of classroom space and classroom activities as learners need to be placed where they can see the boards.
4. Problems can arise for learners who have vision impairments.
5. With age, use of certain types of chalk, and/or improper cleaning practices, boards can become "cloudy" as they retain chalk dust.Overhead Projector
The
overhead projector is probably one of the most versatile and useful
visual aids that has been made available to the modern-day lecturer. The
overhead projector has long since replaced the traditional chalkboard
as one of the main teaching aids and is used in lecture theaters and
classrooms all over the world.
The overhead projector definitely has a number of advantages that would outdo most other visual teaching aids. For instance, a lecturer can use it in just the same way that he or she would use a chalkboard, but the biggest advantage would be that with the overhead projector, lecturers all over the world now get to face the whole class and maintain eye contact all times with their students instead of having to turn around and write. As a teacher, you would know that this eye contact plays a very big role in both facilitative as well as expository teaching, and serves both as a means of receiving feedback from the class on how good or bad the session is and as an outward non-verbal communication medium for the teacher.
The drawbacks of the overhead projector include the basic fact that it requires a constant power supply and also requires a white flat surface on which its image can be projected. Another disadvantage is that if the surface is not suitable inclined at the correct angle, the image will suffer from a phenomenon called 'keystoning'.
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