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Question
How close was your earlier guess? Discuss.
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Solution
Our guess for the stamp was 27, but the actual answer is 28. So, we can say that our guess was quite close to the correct answer.
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RELATED QUESTIONS
Just as precise measurements are necessary in science, it is equally important to be able to make rough estimates of quantities using rudimentary ideas and common observations. Think of ways by which you can estimate the following (where an estimate is difficult to obtain, try to get an upper bound on the quantity):
the number of strands of hair on your head
Match the following.
| Column A | Column B |
| (1) Length | a. kilogram |
| (2) Mass | b. cubic metre |
| (3) Area | c. metre |
| (4) Volume | d. square metre |
Exercise
Length of one’s chest can be measured using metre scale.
Ten millimetre makes one centimetre.
Can you find the diameter of a thin wire of length 2 m using the ruler from your instrument box?
Guess the lengths to draw these things. Ask your friend to draw the same. After you make the drawing use a scale to measure the length. Whose drawing showed a better guess?
| Guess its length and draw |
Measure of your drawing |
Measure of your friend’s drawing |
| An ant of length less than 1 cm |
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| Pencil of length about 7 cm |
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| A glass 11 cm high with water up to 5 cm |
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| A bangle of perimeter 20 cm |
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| A curly hair of length 16 cm |
Difference in size 
Do this for yourself and find the difference.
Measure the yellow rectangle. It is ________ cm long.
Now cut strips of equal sizes out of it. Using tape join the strips, end to end, to make a belt.
How long is your belt? _________
Chumki, Jhumri, and Imran need wire to make a fence.
- How much wire in all will the three need?
There are two beautiful lakes near a village. People come for boating and picnics in both the lakes. The village Panchayat is worried that with the noise of the boats the birds will stop coming. The Panchayat wants motorboats in only one lake. The other lake will be saved for the birds to make their nests.
- How many kilometers long is the actual boundary of lake B?
Give some examples of larger length measures.
The Unit used to measure length ______.
SI unit of electric current is ______.
To measure the distance of a planet from the earth, ______ method is used.
How many astronomical units (A.U.) make 1 parsec?
One parsec is defined as ______.
Which instruments are used to measure very small distances at the atomic scale?
