Teaching Electric Current

I suggest that teachers do not use the model often used where the charges are shown flowing in the conductor.  The problem with this model is that students can be misled in believing that even if the key is open, the current can flow in some parts of the circuit up to the point where the key interrupts it.  Whereas the truth is that the current can flow only if an electric field is established across the conductor, which forces electrons to drift towards the higher potential.  The electric field is established only when the key is closed.  If the key is open, the electric field is not established and the current does not flow in any part of the circuit.   Since the function of the key is to allow or disallow the establishment of electric field, it can be placed anywhere in the circuit.  There is no fixed position for it.  However, many books tend to place the key at a fixed position in the circuit, in many cases near the positive terminal of the battery.  Students should be advised that the key can be placed any where in the circuit and a conscious effort should be made to make circuits in the class room or elsewhere with key at varying positions.

There is another question which students find difficult to answer.  How is that the light of the bulb comes on instantaneously as the switch is put in the ON position?  The reason is that as soon as the electric field is set up, the electrons, wherever they may be in the conductor, start drifting towards the higher potential and the electric current is set up.  The signal that the electric field sends out to the electrons to start drifting travels in the conductor with nearly the speed of light and reaches every where in the circuit instantly, however widespread or far flung the circuit may be.  The signal of the electric field may be likened to the command of a military general.  Once the command is issued, it reaches instantly every where, and the troops in the whole country, wherever they may be stationed, start marching. 

Coming back to the question of the bulb glowing immediately as the switch is closed, once the electrons start drifting, the electron nearest to the bulb gets into its filament, then the next nearest one, and so on.  A current is set up and the bulb glows.  The bulb does not have to wait for the electron near the switch to reach it for it to glow.  It is like opening a water tap.  Water nearest to the tap starts coming out immediately.  We do not have to wait for the water at the other end of the pipe to reach the tap for the water to come out.   

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Promoting Equity in Science Education

1A few suggestions for promoting equity in school science education:. 

                     1.       Reduce syllabi considerably at all school levels.

Reduced pressure of syllabi will give students more time to devote to  fundamental concepts and skills (measurements, drawing and interpreting graphs, etc.).

It is well known to educationists that no worthwhile learning can take place if students do not get time to pause, observe, reflect and imagine.  We also want students to be able to apply the knowledge that they acquire to unfamiliar situations.   For this the thinking skills of students must be sharpened.  To do that they must be given enough time.  This entails that the syllabi must be cut down.

Once the fundamental concepts and skills are properly learnt, the rate of learning can improve in higher classes, since college-going students can take higher pressure. At present students going out of schools have neither grasped fundamental concepts nor have they learned necessary skills.

Pruned syllabi will give more time to students from weaker sections to cope with schoolwork, thereby helping promote equity.

In any case, the conditions in India are so different from one part to another, that it is not possible to imagine that all the schools in India can come up to the same level of achievement.  Keeping equity in mind, it is necessary that the school syllabi at all level be pruned considerably.   

2.   Language of science books should be simple.  

If language of books is difficult, science becomes doubly difficult.  First, the student must comprehend the language and then the concepts expressed in that language.

Every writer of school textbooks should pause at each sentence and question herself, maybe more than once, if she can replace this sentence by a simpler one.  We cannot avoid technical terms, but we can certainly  strive to make the language connecting these terms as simple as possible. 

If the students do not understand the written word, how would they understand concepts of science expressed through these words?  And if they do not understand concepts of science, they would fall back upon rote learning, whereas our objective is to make students think and be able to apply what they learn.

You must have seen the reports that India is falling behind other nations in innovations.  Even much-admired IITs are not doing very well when it comes to innovations.  The reason is that the overall rate of literacy is low and the quality of our ‘literates’ is quite poor.  

Poor language skills of textbook writers and that of students promote rote learning . On top of that, there is little visual support in class rooms. The result is that students stop thinking.  They are unable to apply their knowledge to unfamiliar situations.  Under these circumstances, how can one think of innovations?

One hears complaints from some states (Uttrakhand, for example) that the language of books translated into Hindi is quite difficult.  My request to the lovers of Hindi and other languages is that they should temper their enthusiasm for the language they love and make the language of textbooks easy-to-understand and child - friendly.

The use of simple language makes subject matter accessible to all and thereby contributes to equity.

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Scientific Method and the Role of a Teacher

Scientific Method

Here are the steps of the scientific method.

The scientific method may be a good strategy to teach science in the class room.  Scientists themselves, however, rarely go through this regime.

Intuition, informed guesswork, creativity, an eye for an unusual occurrence, all play significant role in developing new theories, and thereby, in the progress of science.

The Role of a Physics (Science) Teacher

The role of the science teacher is crucial to the development of scientific temper among students. 

•        The teacher should herself be competent in the area she teaches; she must be familiar with all the aspects of the nature of science;

•        She must have imbibed scientific temper herself. 

•        Such a teacher can exemplify the content of scientific temper from her every-day conduct. 

From time to time the teacher can engage her students in discussions (for example, superstitions associated with eclipses) to develop scientific temper among them, and foster among them the values hidden in scientific method; the values like

•        truth,

•        honesty, and

•        open-mindedness.

•        The teacher can help her students to retain and sharpen further the sense of inquiry by allowing them to explore their environment and encouraging them to ask questions, even if sometimes these questions appear trivial, or irrelevant. While teaching she conveys at each stage that science is tentative and nothing is fixed or final and the quest for progressive refinement of theories and explanations continues in which the students can participate at that time and later when they grow old.

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