In the “The Moon and its Gravitation” article (December 13 issue), we discussed misconceptions students have about the concept of gravitation. We had also asked readers to help the students find the right answer. The following article discusses those ideas in detail. The students were asked the following question:

If you’re standing on the moon holding a pen, and you let it go, it will

A. Float away
B. Float where it is
C. Fall to the ground
D. Float towards the earth

(This question is a part of ASSET test, which is a diagnostic test for children. This question was asked to around 3668 students of class 6, across the country. The correct answer is C, the pen will fall to the ground.

Pratham was desperately trying to find an answer to the question. He wasn’t able to decide whether the pen will float towards the earth, float where it is or fall down. His instantaneous response was C; the pen will fall to the ground. But when he heard his friends choosing other options he was puzzled.

We received a response from a reader, Mr Somasundaram, saying that Pratham was correct when he said that the pen will fall down even on the moon. Some readers may be puzzled: Didn't we learn all about the foundations of physics when in school? The answer is "yes" or "no," depending on the interpretation.
The Educational Specialists who had gone to Pratham’s class were shocked to find children saying that the pen will not fall down. They tried to investigate the reason for the incorrect answers.

Dhruv, who said that the pen will float towards the Earth, had a very interesting reason to it. He said, “Just like Earth, even Moon has its gravity. But the gravity of Earth is stronger than the Moon. So, just as a stronger magnet pulls things towards itself, even Earth will pull that pen towards itself because of its greater gravity.”
Manoj who said that the pen will float away in space, gave a reason that the Moon does not have any gravity and moreover, since there is no gravity in space, the pen can float away.

The Educational Specialists were totally bowled over by the reasons given by the students. They were surprised to find such reasons, and questioned children hoping to unearth more faulty reasoning among children . “Why do children think that the pen will float where it was let go?”

Mansi said the pen will float where it was “because it’s mass is very less.” The interviewer asked her, “So what will happen if I drop a heavy hammer on the moon?” She replied, “The moon has a weaker gravity as compared to Earth. But it will still fall down because it is heavy but the pen will not because it is lighter. They both will fall down only if dropped on Earth because Earth has a stronger gravity.”

Isn’t this interesting?

How do children respond in a situation they are unfamiliar with? How do they think in such a situation? What exactly goes on in the minds of students when they are faced with such a situation? These are some of the most challenging questions yet to be answered.

Research shows that when students face such a situation, they tend to answer based on the prior exposure they have had to the concept being asked. If the situation is completely new, as in the one that the students in this case faced, they try and relate it to a similar situation encountered before. The answer may not be totally correct scientifically. But they hold on to it because it satisfies all the criteria they have set in their mind and that fulfills their logical thirst. Any other answer and reason given that might contradict their logic would probably be considered as an error initially. It is only when their own reasoning becomes contradictory that they are able to give up  the incorrect reasoning and accept the correct scientific reason. This can happen only if wrong reasoning is investigated.

In this case, the very basic understanding of gravity seems to be missing - that any two objects, whether they are on earth or anywhere in space, exert a force called gravity directly proportional to the product of their masses; however, it is inversely proportional to the square of the distance between them. In simple terms, as the distance increases, gravity decreases.

A common misunderstanding is that heavier things fall faster on earth than lighter ones because of their mass. But the scientific reason is that it is because of the difference in air resistance, and not the difference in mass! This misunderstanding may play a role in students choosing a wrong option in this question.

Students like Manoj do not seem to have grasped the basic understanding that any object that has mass exerts gravity. Students like Mansi seem to have partially understood the concept.

While students thinking like Dhruv probably try and relate gravity to magnetism and hence end up answering an option that seems to be logical to them but is scientifically incorrect.

Is teaching the right concept enough? Can we be sure that if Sir Isaac Newton himself came and taught this concept, the students would have been clear about the concept? The answer probably would be no! It is important to understand how students think, the reasoning they have, so that the latter part of conveying the concept in an effective manner becomes simpler. We would like you to respond with ideas on how to go about such cases at misconceptions.dh@ei-india.com.


Educational Initiatives, Ahmedabad