Thanks again for the explanation.  After mulling things over today I think it was your simple explanation of the p2p network that cleared things up for me.  I now want to learn a bit more of the technical details of p2p networks, but that's for another day.  As you essentially confirmed, my understandings of mining and transaction fees wasn't too far off, it was just the part about "where" the unconfirmed transactions existed.

As far as feedback.  I've tried to draw on my experiences with the non-technical peoples in my family and can envision a couple of questions.  I hope they can provoke some thought for your presentation.

1.  "So these miners can pick to not include my transaction if they don't want to?"
  --> Your answer for me was perfectly clear as I was already aware of transaction fees.  But, I can forsee some asking about how the fee is set, who sets it, etc.  This might be a good place to add that the "network" agrees upon the rate.  Right now it's X Btc, next month it could be agreed to be Y Btc.  If enough of the participants "decide" upon a change, then eventually the miners will move in step.  (This could also go the other way).  Also, even though you can set a default rate, sometimes you might be asked to vary it, as I've noticed a few times.  Finally, because I can also hear some balking at the idea of including a processing fee, which can initially seem counter-intuitive to the idea of a decentralized currency.  But, even at the current default rate of 0.0005 Btc, that fee is only ~$0.07 (using $135 exchange).  Compare that to Visa/MC/Amex fees or Paypal.

2.  "Why can a block only be so big?"  "Who/what determines the size?"

3. In-line with the reason for my post yesterday, "What happens if I forget to include a transaction fee?"  --> Your post from yesterday generally covers this, but I'm thinking more along the lines of "Will my transaction ever go through?  How long will I have to wait?" Etc., etc.

4.  "Can I add a fee after the transaction has been sent?" --> No.  But I'm sure you know this.

You don't have to answer these here   I'm just trying to step back to when I first started learning about bitcoin and drawing from my explanations/conversations with others.

I'd like to see your presentation when it is done!