Organising demonstration and practical

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{|style="border-spacing:8px;margin:0px -8px" {|width="100%" cellpadding="2" cellspacing="5" style="vertical-align:top;background-color:#f5fffa" ! Introduction 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.
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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
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 * 1) To solve a problem: a) To find V when P & T are given b) To find the specific gravity of liquid/body
 * 2) To explain or make clear by analysis: Role of a catalyst
 * 3) To verify substantiate the review: a) Acid + Base = Salt + Water b) In the absence of light no starch is formed
 * 4) To supply an application: a) Hyperacidity & antacids b) Newton’s II law of motion c) Multiple reflection (360/Ø – 1) = n.
 * 5) 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).
 * 6) To create a problem: Effect of iodine on the growth of tad poles. They die, because, all halogens are poisonous.
 * 7) To show methods & techniques.
 * 8) To display objects and specimens

 Key activities and assignments
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!Criteria of a good demonstration  ! {|width="100%" cellpadding="2" cellspacing="5" style="vertical-align:top;background-color:#faf5ff" {|style="border-spacing:8px;margin:0px -8px"
 * 1) Planned & rehearsed well in advance. a) Apparatus b) Observations c) students trained to help the teacher d) Confidence Ex. NH4 NO2 – N2    + H2O. Only water will remain. So fresh solution must be used.
 * 2) The demonstration must be clear & speedy. Visible to all students, it should be over within 45 minutes depends on different types of reactions.a)Instantaneous reactions–NaOH + HCl b)Delay reactions - KMnO4 + glycerin.c)NaHSO3 + KI03 + (Starch) → cracker
 * 3) Aim of the demonstration should be clear to the teacher
 * 4) It should be done in a scientific way - Arrangement of apparatus must be from left to right, labeling must be checked before hand. No hard and fast rule that while weighing weights must be kept in the right pan. When we are weighing 40 grms of Na2CO3, it can be had on the right pan.
 * 5) Important and difficult points should be stressed and explained well.
 * 6) It should be a cooperative venture of both teacher and students
 * 7) It should be followed by question & answer or discussion.
 * 8) Time & season must be kept in mind.a)Static electricity experiments will not be successful on rainy days, as production and discharge will be fast
 * 9) Failure – Then convert it into a problem and find out the causes
 * 10) It should pose problems and make provision for solving it – It should provide a chance to exercise their abilities to observe, explain, analyse, verify and review.
 * 1) Failure – Then convert it into a problem and find out the causes
 * 2) It should pose problems and make provision for solving it – It should provide a chance to exercise their abilities to observe, explain, analyse, verify and review.
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 b) NaCl + AgNO3 → AgCl + NaNO3. In summer white AgCl becomes light grey, green, brown and black.  