NCERT Solutions for Class 4th Maths Chapter 11 . Making a paper airplane — Let Us Do
Book page 1652 Updated on2026-09-19
Q1.
Mark the line of symmetry in Fig. 3, Fig. 4, and Fig. 5.
Answer
In all three figures the line of symmetry is the middle crease that runs from top to bottom.
The paper at three steps of making the plane.
Here are the same three figures with the line marked:
The line of symmetry marked with a dashed red line in each figure.
Why it happens: The very first step was to fold the sheet in half. Every later fold was made the same on both sides of that crease, so the crease stays the line of symmetry.
Q2.
How many lines of symmetry can you see in Fig. 8?
Answer
Fig. 8 has 1 line of symmetry.
Fig. 8 — the plane opened out, showing all its crease lines.
Number of lines of symmetry in Fig. 8 = 1 It runs from the top middle straight down to the bottom.
The one line of symmetry of Fig. 8.
Why it happens: Every crease made on the left has a matching crease on the right, at the same slant. No other fold of the sheet makes the creases match.
Q3.
Where will you place a mirror to see the reflection of the right half side of Fig. 8? Will it look the same as the left half side?
Answer
Stand the mirror upright on the middle crease of Fig. 8, facing the right half.
The mirror is kept standing on the dashed middle line.
Yes — the reflection looks exactly like the left half side.
Why it happens: The middle crease is the line of symmetry. A mirror kept on a line of symmetry always shows the other half of the shape.
Try This: Now turn the mirror around and face it towards the left half. You will see the right half in it.
Q4.
Fly the plane.
Answer
Hold the plane by the middle crease, below the wings. Point the nose a little upward and throw it forward gently.
Check that both wings are of the same size.
Hold it at the crease so that both wings stay level.
Throw it smoothly — do not jerk your hand.
Sample answer: My plane flew straight for about 6 steps and then came down slowly.
Why it happens: Both wings are the same, so the air pushes both of them equally and the plane goes straight.
Q5.
Will the plane fly if there is no line of symmetry?
Answer
It will move, but it will not fly straight. It turns to one side and falls quickly.
If one wing is bigger, that side is heavier and catches more air.
The plane leans to that side and starts turning.
It loses height fast and lands near you.
Why it happens: A plane needs the two halves to be alike. When the two halves are not alike, the air pushes one wing harder and the plane tips over.
Q6.
Try to make an asymmetrical plane.
Answer
Make a plane in the usual way, then change only one side.
Fold a fresh sheet and make the plane up to Fig. 7.
Now cut about 2 cm off the tip of one wing only.
Or fold one wing down a little more than the other.
Sample answer: I cut one wing shorter. Now the two halves do not match, so the plane has no line of symmetry.
Check it yourself: Try to fold the plane in half. The two wings will not sit on each other.
Q7.
Fly both the planes and see which plane flies for a longer time.
Answer
Throw both planes the same way, one after the other, and count aloud until each one lands.
Plane
How it flew
Count till it landed
Symmetrical plane
Straight and smooth
about 5
Asymmetrical plane
Turned to one side
about 2
Sample answer: The symmetrical plane flew for a longer time.
Why it happens: Matching wings share the air push equally, so the plane stays level longer in the air.
Q8.
Share your observations with your friends.
Answer
Tell your friends what you saw. You can use these three lines.
The plane with a line of symmetry flew straight and stayed up longer.
The plane without a line of symmetry turned to one side and fell soon.
Symmetry is not only pretty to look at — it also helps things work well.
Did you know? Real aeroplanes, birds and kites all have matching left and right halves for the same reason.