One Potentiometer, Six Weeks, Thirty-Two Candidates
A newly posted PGT Physics joins an EMRS with 32 Class XII students, 26 of them first-generation learners. The laboratory is a 9 m × 6 m room holding four working rheostats, two ammeters, one 12 V battery eliminator and a single 0–30 V power supply; six students share a bench built for two. The CBSE practical examination is six weeks away, and each candidate must perform one of the 15 prescribed experiments before an external examiner. Only two 40-minute laboratory periods are timetabled each week, and they clash with the evening games slot, so attendance in the past fortnight has fallen to about 60 per cent. A single potentiometer wire is claimed by four students who have chosen EMF comparison as their project. On the 18th the school is inspected, and the principal wants every practical record book complete and signed, remarking that 'earlier batches managed it somehow'.
1. Build a six-week laboratory plan that gives every student real hands-on work. Show the time arithmetic and state explicitly what you sacrifice.
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Arithmetic first: 6 weeks × 2 periods × 40 minutes = 480 minutes, i.e. 8 hours of laboratory time shared by 32 students - about 15 minutes each in total. Because there are only two ammeters and one power supply, at most two circuits can run simultaneously, so roughly 6 students can be hands-on per period: 12 periods × 6 = 72 student-experiment slots, or about two personal performances each.
Plan:
- Weeks 1–4: two live circuits, groups of three, 20 minutes per turn; the remaining students complete structured observation sheets at their benches rather than idle copying.
- Every student performs at least two experiments personally and observes at least eight.
- The potentiometer becomes a whole-class demonstration bench in week 3, with the four claimants taking readings in turn.
- Weeks 5–6: mop-up, viva rehearsal, record completion.
Sacrifice: I would drop the two experiments for which apparatus genuinely does not exist and replace them with the NCERT alternative-method demonstrations, recorded honestly as demonstrations. The record book then reflects what happened, and every candidate still has a performable experiment and a defensible viva answer.
2. Four students need the only potentiometer at the same time. How do you allocate it, and what do the other three do meanwhile?
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Allocation must be transparent and rotating, not first-come. I would post a written slot chart: each of the four gets one 20-minute turn per week across three weeks, order decided by lot in front of the class, so nobody can claim favouritism. Each slot-holder is paired with one of the other three, who reads the galvanometer and records the deflection - so all four are inside the same experiment, not waiting outside it.
Meanwhile the non-holders do the voltmeter–ammeter comparison of two cells, which gives an independent estimate of the EMF ratio. That is useful rather than filler: when the potentiometer result and the voltmeter–ammeter result are compared, students see why the null method is superior, since the voltmeter draws current and depresses the terminal voltage. This converts an apparatus shortage into a conceptual gain.
I would also check the potentiometer wire for uniform contact and clean the jockey before rotation begins; a single bad contact early in week 1 will destroy six weeks of readings and confidence.
3. The principal instructs you to have all record books 'complete and signed' by the 18th. What do you do and what do you actually say?
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I would not sign observations that were never taken. Fabricated readings create a real external risk: the examiner questions candidates on their own recorded values, and a student who cannot explain a column is more exposed than one who admits an experiment was demonstrated. Beyond that, the message to first-generation learners that records are paperwork to be manufactured rather than evidence of work done is corrosive.
What I would say, in a short written note to the principal: here is the count of experiments completed per student (real numbers), here is what remains, here is the additional time requested. Because this is a residential school, the most realistic request is four evening study slots of 45 minutes converted to supervised laboratory work - 180 extra minutes, which nearly doubles the hands-on allowance. I would also propose that the inspection file show the honest completion chart and the recovery plan; inspectors generally respond better to a documented plan than to uniform, suspiciously perfect notebooks.
If the pressure continues, I would put the request and my refusal in writing and copy the academic coordinator, keeping the tone factual rather than defensive.