NCERT Solutions Poorvi Chapter 3 My Brother's Great Invention — Let us discuss

Book page 94 & 95 Updated on2026-09-05

Q1.
I Complete the cause-and-effect table given below. (1) Cause: Anand set up his burglar alarm and rigged it to work when the door was opened softly. (2) Effect: Anita was able to avoid any responsibility as Anand faced the consequences alone. (3) Cause: We watched the movie 'Back to the Future'. Effect — Anand: (4) Cause: Papa firmly said 'NO' to trying out the time machine.
Answer
CausesEffects
1. Anand set up his burglar alarm and rigged it to work when the door was opened softly.Papa, who always opens the door gently, tripped the alarm himself. The bell clanged, the water bag came loose and he was left standing on the doorstep 'sopping wet and scowling'. He roared for the boy, and Anand vanished until after dinner.
2. Anita warned Anand in advance — 'If you get a shelling, don't bring me in' — and kept repeating, 'Remember, if Papa asks, I'm not involved.'Anita was able to avoid any responsibility as Anand faced the consequences alone.
3. We watched the movie 'Back to the Future'.Anand: decided that he had to build a time machine too. He shut himself in his room for a fortnight, turned it into a network of wires, springs, levers and bulbs with an enormous control switchboard, took apart the household gadgets for parts, and stopped even combing his hair. 'That was the end of peace and quiet in the house.'
4. Papa firmly said 'NO' to trying out the time machine.Anand looked crestfallen, so Ma persuaded Papa to at least take a look at it. The trial had to be put off — and because the parents left for a wedding at Kharagpur the next day, Ma made Anand promise not to touch the machine till they returned.
Tip: In a cause-and-effect table, the effect must be traceable to the cause in the text itself. Quote the line that proves the link, the way 'sopping wet and scowling' proves effect 1.
Q2.
II Do you think Anand was able to keep his promise regarding the time machine? If yes, why? If no, why not?
Answer

Yes — but only by accident, not by choice. Anand never switched the machine on himself. He promised Ma 'half-heartedly, offended at this lack of respect for his creation', and then fell asleep the moment his parents left. The machine was started that night by Boppa, the thief, who blundered into the dark room and hit the switchboard: 'My time machine, he's started it!'

Why it happens: The story is careful to keep Anand technically innocent. He is locked in the other room the whole time, shouting for help. So the letter of the promise is kept — but the spirit of it is very shaky, because Anand had no intention of waiting. He was already itching to test the machine: 'I wish we could get out of this room and see what is happening out there.' Given one more quiet night, he would almost certainly have broken it.
Try This: Write two sentences arguing the opposite view — that he did not keep the promise, since the machine was run in his house, on his watch, in his absence from bed. Both answers can be defended if you quote the text.
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