Teaching Tips - The Art of Misleading

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Teaching Tips - The Art of Misleading

2005-11-03T17:30:00

Every teacher will have a bag of `tricks' he is particularly fond of. Let me tell you about a personal favourite. The idea is this - put in your most serious look and really, really convince the audience that what you are saying is absolutely true. Say you are teaching concurrency control to a newbie audience - just show them the incorrect implementation of a spin lock:

int lock = 0;

void acquire_lock()
{
    while(lock);
    lock = 1;
}

void release_lock()
{
    lock = 0;
}

Now argue eloquently about how writing your critical sections like this:

acquire_lock();

critical section

release_lock()

makes them mutually exclusive. The really attentive guys will think about what you are saying and you will see a look of disbelief appearing on their faces - ignore them for a moment - the others will get convinced that what you are saying is true - some would have even started writing down your words of wisdom. Now, stand back and announce (with proper dramatic effect) that, "OK guys - you have been listening to absolute crap for the past 5 minutes". Enjoy the reaction on their face! Don't overdo this trick - or your audience will get the hang of it and *always* assume that the opposite of what you are saying is true. The idea is to mislead occassionally so that the listener is never able to guess whether you are misleading or not! The psychology behind the trick is this - the fact that a chain of logical reasoning is wrong sinks in more deeply when you are convinced that it is right!