The Light Is Better Here
(And That’s Okay)
A KERNEL OF TRUTH
by Jim Huggins,
When I teach recursion in CS2, I start with all the traditional examples that appear in most textbooks:
the exponential function, the factorial
function, the Towers of Hanoi, and so on.
Towards the end of the lesson, I feel the
need to apologize to them for offering such
trivial examples. By way of apology, and of
explanation, I tell them this old story:
A police officer sees a drunken man
intently searching the ground near
a lamppost and asks him the goal of
his quest. The inebriate replies that
he is looking for his car keys, and the
officer helps for a few minutes without success then he asks whether
the man is certain that he dropped
the keys near the lamppost.
“No,” is the reply, “I lost the keys
somewhere across the street.” “Why
look here?” asks the surprised and
irritated officer. “The light is much
better here,” the intoxicated man
responds with aplomb. [ 2]
And so, I explain that, yes, these simple
examples could be done more simply with
iteration, but that more difficult examples
will come later (like binary search trees), and
practicing the technique “where the light is
better” will make that transition easier.
I wonder if I should stop apologizing.
It seems my whole educational life has
been filled with exercises that I completed
not because the answer was important,
but because the journey to the answer was
important. I practiced Bach Inventions at
my piano to learn dexterity and technique,
Theorem to learn how to construct a math-
ematical proof, not because anyone is in
doubt regarding the theorem’s reliability.
When I enter the classroom, I feel pressured to demonstrate the relevance of our discipline to my students. And so, I strive to find
assignments that demonstrate the wonders
of our discipline while remaining accessible to
novitiates. But maybe it’s okay, occasionally, to
let our students know that we’re giving them
an exercise whose purpose is to help them
hone their skills. There’s plenty of room for
letting students practice how to average a list
of numbers [ 1], even as we get them ready for
something more “nifty” [ 3].
Sometimes, it’s okay to search where
the light is better. It’ll help us learn how to
search in poor light, too.
1. Fisler, K. 2014. The recurring rainfall problem. In
Proceedings of the tenth annual conference on
International computing education research (ICER
‘14). ACM, New York, NY, USA, 35-42.
2. O’ Toole, G. “Did You Lose the Keys Here?” “No, But
the Light Is Much Better Here.” Quote Investigator;
light/. Accessed 2017 March 30.
3. Parlante, N., Nifty Assignments; http://nifty.stanford.
edu. Accessed 2017 March 30.
James K. Huggins
Computer Science Department
1700 University Avenue
Flint, MI, USA
DOI: 10.1145/3078297 Copyright held by author.