Finding the longest day with school children

I wrote this article a while ago for a school souvenir. I got delayed in posting it here since I wanted to put a picture of the plot of duration of the day that students came up with. I still don’t have the picture, but I decided to post it and update it with the picture whenever it is available. Click here for the pdf of the article.


Date: 21st Dec 2012.

During the year 2011-12, I interacted with students of Purnapramati [1] only once or twice, but I really enjoyed my time with them. I wanted to interact children more regularly this year. So, after discussing with Indumathi akka [2], the science teacher of the school, we thought it would be nice to work on a short-term project where students get some hands-on experience of learning science. Exactly six months ago, on 21st of June 2012, I began interacting with students of 5th class of Purnapramati.

As I kept thinking what could be a feasible short-term yet interesting thing that primary kids can do, I was already in the class and I began my interaction by exchanging greetings. But the answer was elusive until our interactions gained some momentum.

I asked students, “Is today any special day?”. The answer came almost immediately when one student said “Today is summer solstice”.

I then asked the student back, “I have never heard of that. What does that mean?”

One other student laughed and said, “Don’t you know, it is the longest day of the year”.

“May be, but how do you know about this fact?”, I asked.

“We learnt in the class. Our teacher told us”, came a response from one corner.

“How did your teacher know about that?”. I continued my questions.

“From her teacher” was one answer while the other student said “From our text book”.

“How did your teacher’s teacher or even the text book writer knew that 21st June is the longest day in the year?”.

Although I immediately heard the answer “From their teachers”, it was already clear to some students that I was going to ask “How did that teacher come to know?”

After teasing their minds for a bit, I got the answer I was waiting to hear when I one student said “someone must have measured length of day all throughout the year and found it out”.

I then told students, what if your teacher had never told you that June 21st is the summer solstice? If our challenge is to find it out yourself, how will you do it?

I got to hear a lot of creative and courageous solutions which ranged from how they will wake up and note down sunrise time and also sunset time every day. When I asked how can they see precise time of sunrise or sunset if there is a huge building next to their home, some volunteered to go to mountains and deserts where one can see horizon to horizon. Some even thought of setting up automatic devices that will record sunrise and sunset times automatically.

Finally, we all agreed to take a short-cut given difficulties of going out of home to a desert or even that of waking every morning without fail. The short-cut, as suggested by students themselves, was to look at the newspaper (or panchanga) everyday and note down sunrise and sunset times.

Once the concept for the project was ready, it was time for implementation and that took nearly three to four months, working on this at a frequency of twice a month (sometimes even less).  For this class of 12, each student was assigned a specific month and was asked to note down sunrise-sunset time from newspaper collection at their home. Based on that they calculated daytime duration (which they learnt in the process of our project). They also learnt how to use graph sheets and produced nice plots of duration of daytime for each day of their month.

When they finally put together all those data mostly on their own with occasional help from Indumathi akka (science teacher) and myself, we were all extremely fascinated to see the oscillating pattern of duration of the day. Students immediately went back to the original motive of our project, and found based on their own analysis that the duration of the day was maximum for about 10 days towards last two weeks of June. So it was not one day when it was maximum, but for 10 days!

It was probably in all students’ mind as to why does everyone say June 21st as the longest day of the year when there are 10 days that are longest. But they had figured the reason discussing among themselves; they had data of sunrise-sunset only up to minutes accuracy. To find which day of among those 10 days were longest, they said they would need data of sunrise-sunset time unto seconds, or even milliseconds.

While it is clear what students learnt from this exercise, it was also extremely interesting to interact with students, answer their amusing and intelligent questions. It was also revealing to me to learn finer details of such simple facts, which we all take for granted.

[1] Important Disclosure: The school is founded by close relatives and friends. You can learn more about it by visiting the website:

 [2] Teachers are affectionately called akka (meaning sister) or anna (meaning brother) in this school.


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