From: Claire (for Teacher2Teacher Service)
Date: Mar 04, 2008 at 20:25:45
Subject: Re: Probability with dice

Hi, Joe --

Thanks for writing to T2T. Probability challenges many people, myself
included. I have a couple of ways I've handled just this issue -- with
teachers as well as students!

Think about using two different colored dice. I roll a red one, you roll a
green one. For each of the six ways my red one can land, your green one can
land in six different ways. Think about it as a 6 x 6 grid. That tells us
there are 36 different outcomes, 30 of them "turn-arounds" and 6 of them
doubles.

I can roll a red 3 at the same time you roll a green 5. We count that as a
different outcome (a way the dice can land) than when I roll a red 5 and you
roll a green 3. When we both roll 5s, there is only one way for that to
happen.

There is a web applet that may help:
http://nces.ed.gov/nceskids/chances/index.asp
It simulates the sum of two dice with as many rolls as you like. Scroll down
to see the 36 outcomes listed.

You and your students can learn more about probability at the Ask Dr Math FAQ
page:
http://mathforum.org/dr.math/faq/faq.prob.intro.html

I hope this is helpful. Please write again if you have more questions.

 -Claire, for the T2T service

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