Introduction
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Giving demonstration has become an important activity these days, after the IT age has ushered in. This is a situation where the teacher organizes the apparatus and materials and make them work. He will have arranged the demonstration in such a way that every body in the audience can see the working. It can be a computer or a mobile or preparation of chlorine gas or working of a thermo meter. The Lecturer plans it well and students enjoy seeing the working. The visual is always better than mere listening in a lecture situation.
Overview
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Contents/Sub-units
- Meaning of demonstration, functions of a demonstration
- Criteria of a good demonstration
- Requisites of a good demonstration
- Advantages of good demonstration
- Meaning of practical/development of skills
- Organisation of practical work
- Criteria of good practical work
- Assessment of practical work
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Objectives
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After going through this unit you will be able to:
- Define a demonstration
- List the advantages of a demonstration
- Enumerate the criteria of a good demonstration
- Define the practical work in a laboratory
- Plan to organize good practical work
- List the criteria of a good practical
- Construct test items to assess the practical work
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Meaning of demonstration
Demonstration means ‘to show’ or give the proof of, to prove or establish the truth. In a science or arts class demonstration implies showing the apparatus, arrange them in proper order so that it works. To give a demonstration means to show that required thing with verbal presentation to make the point clear or show how the machine works. It can be a water purifier or vacuum cleaner or laboratory apparatus.
Functions of a demonstration
- To solve a problem: a) To find V when P & T are given b) To find the specific gravity of liquid/body
- To explain or make clear by analysis: Role of a catalyst
- To verify substantiate the review: a) Acid + Base = Salt + Water b) In the absence of light no starch is formed
- To supply an application: a) Hyperacidity & antacids b) Newton’s II law of motion c) Multiple reflection (360/Ø – 1) = n.
- To evaluate student’s achievement: a) Effect of varying light in intensity on photographic plate & growth of a plant b) Reaction of magnesium powder and ice-no reaction, Add dry ice reaction takes place. Hence dry ice acts as a catalyst. (Even water, ice, steam also act as catalysts).
- To create a problem: Effect of iodine on the growth of tad poles. They die, because, all halogens are poisonous.
- To show methods & techniques.
- To display objects and specimens
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Requisites of a good demonstration
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The following must be kept in mind before doing the demonstration, by the lecturer.
- Physical facilities like demonstration table, light or darkness, Gas/Water/Burner facilities. Benches/Desks arranged in stairs/gallery, and a good black board.
- Apparatus and chemicals:Apparatus must be large, simple, improvised and reserve set, if the demonstration fails. Chemicals must be pure, clearly distinguishable and substitute if the demonstration fails
- Purpose of the demonstration must be clear to the teacher.
a) Teacher must have the list of apparatus & chemicals
b) Principles, theories and formula related to the demonstration
c) Observations
d) Graphs
e) Inference
f) Applications (Problem solving)
g) Important points (Precautions)
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Merits of good demonstrations
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The following merits can be listed in case of good demonstrations.
- Demonstration make the ideas concrete
- Students learn better and they retain it for a long time
- It is economic as the lecturer shows the adjustment of apparatus and the theory or law can be taught to a large number of students.
- It is cheaper than individual laboratory method
- Learning will be better even though it is slightly costlier than lecture method
- There is higher degree of motivation in students, and concentration will be better. (Visuals are remembered for a long time compared to the words)
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Organisation of Practical work
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Meaning of practical work
Practical work is opposed to mere theory, practical work is doing the established method, or practicing the skill. In a pre-university college, practical work is supplementary to the theory that is taught. Practical work is arranged in the colleges and students go to the laboratory in groups and do the practical there. The exercises are more in the form of verification than open – ended inquiry type. But these exercises develop the skills of laboratory work.
The skills are developed in four stages
- Demonstration by a master crafts man
- Imitation by the students
- Practice and Correction by the lecturers
- Internalization, where students automatically do the experiments and the skills are interwoven in the practical work. The pre-university students do these experiments and learn the skills well.
Organisation of Practical work
The lecturer with the help of an attendar has to plan for the activities in the laboratory. The number of students who will be attending the laboratory will have to be kept in mind, while arranging for the sets of apparatus required and the amount of chemicals needed. The special reagents that are required, the light/darkness needed, etc must be kept in mind while arranging for the special type of experiments. The lecturer will have made arrangements as to who will work where, so that there will not be any confusion what so ever.
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Assessment of Practical work
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Assessment of Practical work
Practical work can be assessed through a paper – pencil test. The parameters that can be tested are the following.
- Were the apparatus and chemicals available?
- Were the apparatus clean and usable?
- Were the chemicals clean and fresh?
- Were there reserve sets of apparatus if there was any problem?
- Were there substitute chemicals, if the chemical used failed to work.
- Was the teacher ready with list of observations, graphs applications, etc.,
- Was there opportunity to pose the problem and search for the answer?
- Were there avenues to raise the questions and look for the responses?
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