TITLE: Learning from Failure
AUTHOR: Eugene Wallingford
DATE: December 09, 2004  5:05 PM
DESC: People are drawn in by negative stories to learn something new.  Telling positive and negative stories, then, becomes a necessary skill for teachers.
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BODY:
I have a couple of things on my blogging radar, but
<A HREF="http://nat.truemesh.com/archives/000442.html">
   this quote</A>
from Nat Pryce just launched a new train of thought.
Maybe that's because I gave my last lecture of the
semester an hour and a half ago (hurray!) and am in
an introspective mood about teaching now that the
pressure is off for a while.

<BLOCKQUOTE>
One of the many interesting topics that Dave [Snowden]
touched on [in his talks at
<A HREF="http://www.xpday.org/">
   XP Day 4</A>
was how people naturally turn to raw, personal stories
rather than collated research when they want to learn
how to solve a problem.  Furthermore, people prefer
negative stories that show what to avoid, rather than
positive stories that describe best or good practices.
</BLOCKQUOTE>

This "struck a chord" with Nat, whose blog is called
<I>Mistaeks I Hav Made</I> [sic].  It also struck a chord
with me because I spend a lot of my time trying to help
students learn to design programs and algorithms.

When I teach patterns, whether of design or code, I
often try to motivate the pattern with an example that
helps students see why the pattern matters.  The decorator
pattern is cool and all, but until you feel what <I>not</I>
using it is like in some situations, it's sometimes hard
to see the point.  I think of this teaching approach as
"failure driven", as the state of mind for learning the
new idea arises out of the failure of using the tools
already available.  It's especially useful for teaching
patterns, whose descriptions typically include the forces
that make the pattern a Good Thing in some context.  Even
when the pattern description doesn't include a motivating
example, the forces give you clues on how to design one.

I taught the standard junior/senior-level algorithms course
for the first time in a long, long time this semester, and
I tried to bring a patterns perspective to algorithm design.
This was helped in no small part by discussions with
<A HREF="http://www.tau.ac.il/education/homepg/ginat.html">
   David Ginat</A>,
who is interested in documenting algorithm patterns.
(One of my favorites of his is the <I>Sliding Delta</I>
pattern.)  But I think some of most effective work in the
algorithms class semester -- and also some of the most
unstructured -- was done by giving the students a game
to play or a puzzle to solve.  After they tried to figure
out the nugget at the heart of the winning strategy, we'd
discuss.  We had lots of failures and ultimately, I think,
some success at seeing invariants and finding efficient
solutions.  The students were sometimes bummed by their
inability to see solutions immediately, but I assured
them that the experience of trying and failing was what
would give rise to the ability to solve problems.

(I still have more work to do finding the patterns in the
algorithms we designed this semester, and then writing
them up.  Busy, busy!)

Negative stories -- especially the <B>student's own</B>
stories -- do seem to be the primary catalyst for learning.
But I have to be careful to throw in some opportunities
to create positive stories, too, or students can become
discouraged.  The "after" picture of the pattern isn't
enough; they need to phase a <I>new</I> problem and feel
good because they can solve it.  I suppose that one of
the big challengers we teachers face is striking the
right balance between the failures that drive learners
forward and the successes that keep them wanting to be
on the road.
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