Berries, branches and brainwaves

Geetha Nadarajan

Teaching concepts in physics always used to challenge me and every time nature helps me. For many of the concepts, the journey from the concrete to the abstract also comes with taking examples from nature.

“Newton’s First Law states that an object will remain at rest or in uniform motion in a straight line, unless acted upon by an external force.”

The children in upper middle school were reading this law in the textbook, and there were multiple questions: “Does it refer to us taking rest? What is uniform motion in a straight line? Why has the “straight line” come in the law? Will this appear in the exam? I did not understand, aunty.”

As and when they were asking these questions, my mind was buzzing with the question: ‘How to make it contextual?’ I was sure that the answer will be there, right out in nature – Prakriya Green Wisdom School’s best resource (and the best teacher).

No sooner did I recall this image of children next to the tall gooseberry tree, constantly trying out different methods to pluck gooseberries, did the idea of taking an outdoor class flash through my head – unsure as I was of this working out.

The entire class gathered around this gooseberry tree full of berries. I asked the children to come up with different ways to get the berries off the tree and said that they could demonstrate their ideas. One of them immediately came forward, held a thin branch of the tree and started shaking it. It started raining gooseberries. I asked them if they could relate this act with Newton’s First Law? One child shared that the gooseberries were at rest when we arrived, and they wanted to remain at rest forever. “So along came the external force as “Unni” started shaking the branch …”

I completed this sentence by saying, “The berries wanted to remain at rest, the branches were moved by an external force, this pull and push made the berries detach from the stalk.” Thereafter, reading the law a couple of times helped them to relate to this law in a better way.

Distance and Displacement, Is there any difference?
In class 7, we were learning the concept of distance and displacement. We started this as an activity-based learning. The children were asked to run between two fixed points where they can decide the path to reach the other end by starting at one. As and when the group is conducting this activity, one person will observe the different ways chosen by the group so that he/she can explain this in the class. After sharing this in the class, a discussion was carried out on the different ways to reach from one point to another. The discussion was then consolidated to explain that the shortest among this is called ‘displacement’ with the help of a few drawings on the board.

The concept is again reinforced by giving out the definition of both as the following:

• Distance is the actual length travelled by a moving object.
• Displacement is the shortest possible distance travelled by a moving object between the initial and final points.

If the initial and final point is the same, then the displacement invariably becomes zero whereas the distance may not.

In all these explanations there was one child who still had a doubt about this concept. His name was Srivinaayak. I asked him to listen to an incident: Imagine that I have asked you to do me a favour by returning a book to the main library (Prakriya has two libraries) after meeting the librarian and sharing the information that I have asked you to do it. Thereafter you must go to the second library and ger a reference book about flora and fauna and hand it over to me in the staffroom. After some time when I come back to the classroom, I see you sitting on the same bench in the same place. What will be my first reaction? The question was opened to the class. They started responding, “You didn’t even get up from your place?”, “I asked you to do the task now, not anytime,” “Srivinaayak, you need to be responsible,” etc. To this I also responded as I see Srivinaayak is not displaced from his place or is seated in the same place, I would have assumed that he has not done the work. The story does not end here. To my surprise, with a smile, Srivinaayak takes the book from his bag and hands it over to me and answers that he has finished the task of returning the book by going to the main library and picked up the book by going to the second library and came back to the class and was about to meet me in the staffroom.

I thereby added, as the initial and final position of Srivinaayak is the same, he has not made any displacement, or the displacement is zero. The actual distance covered in this situation is adding the distance from the classroom to the main library with the main library to the second library and then the distance from there to the classroom. (The concept of scalar and vector is taught thereafter).

The author is a facilitator, Prakriya Green Wisdom school. She is passionate about exploring different ways in approaching science learning. She can be reached at geethanadarajan.prakriya@gmail.com.