A rare fun math class

I taught my kids how to make change several years ago, but it came up again today in Noah's consumer math book, so I thought it would be a good time for a refresher.  It was a very boring, dry lesson, and the work consisted of questions like, "A customer owes $7.36 and pay you with a ten dollar bill. Write down which coins and bills you would use to make change."  Who would want to write that out? 

So I set up a store with priced items and a cash register with various bills and coins.  When Noah woke up, I gave him a $20 bill and invited him to shop.  He bought his own shirt (that I had just removed from the dryer) for $8.72, and I demonstrated how to make change.  I gave a little speech about how it's still an important skill to have, even in this era of computerized cash registers and credit cards.  I gave some personal examples of when I've needed to make change (when the cash register broke at the thrift store where I work, and when someone bought something from me at a garage sale). 

Then I shopped, and he made perfect change.  One time I owed him $18.37, and I gave him a $20.  He started to make change, but I pretended to be a cranky old person and said, "Hold on now.   I don't want all those coins. I've got the change here somewhere...." and proceeded to fumble around until I found 37 cents.  He looked paralyzed.  He said, "You gave me too much money.?"  I said, "That's how a lot of old people like to do it.  So now you have to subtract what I owe from what I gave you, and give me the difference." One of the things I priced was his Epipen (it was out because he has allergy shots today, so I just stuck a price tag on it and put it in the store).  So I came into his store, pretending to be in anaphylactic shock.  I grabbed the Epipen, tossed him a $20 bill, and collapsed on the floor.  He said, "Out of $20...and 50 cents makes 19, and a dollar makes 20.  Have a good day!"  I said, "Fail.  I'm dead. You were supposed to administer the Epipen, not make perfect change!  If someone comes into your store near death, making change is not your top priority." 

All of this took about 15 minutes.  I closed the math book and put it away.  He said, "We're not going to do math?"  I said, "We just did."  He smiled and said, "Thanks...that was fun!"