This teachers' day, I fondly remember a teaching tale from my time as an economics teacher at Akal Academy, Baru Sahib in 2017.
February 25, 2017
Grading the answer scripts of the last statistics test, I noticed a wide variety in the marks scored by the students. There was an outlier on the lower end – a student who had done unusually bad on that test.
Today’s revision class was on the topic of
dispersion.
After distributing the graded answer
scripts, I tell them ‘Okay, let’s calculate
the mean marks scored by your class’
They ask around for each other’s scores. To
prevent confusion, I announce the list of scores. They sum up the scores,
divide by the class strength and tell me the answer.
Bravo!
Now lets calculate the range. Do you know the formula for range?
They quickly quip “H – L”
“Who scored the highest?” They look around
and ask. “And the lowest?”
They find the two values and the range is
calculated. I am told that on this 20-mark test, their class range was 16.
Woah,
that’s quite large. Do you know that the other section had a range of 7 on this test.
This means that their section is ‘less unequal’, they have less dispersion in
their scores.
Next
time, I want your class to have a higher mean and a lower range. Will you do
that?
They nod with thoughtful looks.
Suddenly, I notice eyes full of concern for
the girl who had scored the lowest. ‘Prabh – we will help you in the next test,
you must improve!’
I had goosebumps. That was something I had
not expected to happen. They realised that that the only way the range could be
decreased without pulling down the mean was by raising the lowest score. And
the concern had sparked empathy and a new sense of care in my class.
The chapter on dispersion could be so
powerful. That was the greatest lesson I learnt from my students that day.
***
