NCERT Solutions for Class 4th The World Around Us Chapter 7 Does shape play a role? — Activity 4
Book page 112 Updated on2026-09-19
Q1.
Let us find out whether shape plays a role in floating and sinking.
Answer
What to do
Cut three pieces of aluminium foil of the same size.
Leave the first piece spread out flat.
Press the second piece tightly into a small ball, squeezing out as much air as you can.
Bend the third piece into a cup shape, like a small katori.
Guess first, then put each piece gently into a bowl of water and watch.
Set-up: take three equal pieces of aluminium foil and give each one a different shape.
The completed table
Aluminium foil when—
Before dropping — What is your guess?
Before dropping — Why do you think so?
After dropping — What is your observation?
After dropping — What could be the reason?
spread out
F
It is thin and light
F
It lies spread wide on the water
pressed tightly into a ball
F
It is the same foil, so it should still float
S
All the foil is squeezed into a small space and no air is left inside
in a cup-like shape
F
A cup is like a small boat
F
The cup holds air inside it
What this activity teaches: the book states it plainly — By changing the shape, we can make an object float or sink. When aluminium foil was spread out or made in the shape of a cup, it floated. However, when it was made into a ball, it sank.
Why it happens: The foil weighs the same in all three tests. Only its shape changed, and that alone decided whether it floated or sank.
Tip: Press the ball really tightly. If air stays trapped inside, the ball may float too.