I’ve started giving my 5-year old an allowance of \$2 per week. Last week he didn’t get to spend any of his money. So before going to a flea market I reminded him that he had not \$2, but \$4 (\$2 from last week and \$2 from this week) in his “account”.

His first reaction was “Wow, that’s really a lot of money!”.  Next, he switched into his inquiring mode:

DS: “Can I spend all of it?”

Me: “Yes, but then next week you will only have \$2″

DS: “Ok, what if I only spend \$1 this week?”

Me: “Then you will have \$3 left and then next week you’ll get \$2 more. Do you know how much you will have?”

DS: “How much? A million?!”

Me: “Not quite. See if you can count on your fingers. Three and two more”

DS: “That is \$5″

Me: “Yes. But that’s if you only spend \$1 today. If you spend \$2 today, you will have \$2 left and will get \$2 more next week for a total of … \$4″.

DS (excitedly): “Mama, money is like mathematics!”

Me (even more excitedly): “How so, honey?!”

DS: “When you get money, it’s like addition. When you take money away, pay, it’s like subtraction!” (Jumping up and down now) “This is good. So like mathematics!”

This was a terrific moment of discovering math outside of our books and manipulatives (which are great, but not something you come across outside of a classroom or a teachers’ store).

So now I’m thinking about math games that involve money and making a list. So far I have this:

1. Sorting the contents of our piggy bank

2. Lining up pennies to show how many are in a nickel, a dime and a quarter (doing that with all coin denominations, actually)

3. Grouping pennies by 10 (since my son can count to 10 confidently) and figuring out how many groups of pennies we have.

4. Penny toss – this is an idea from Peggy Kaye’s “Games for Math” book. Draw a game board with 8 sections, each with a number between 1 and 10 in it. Then take turns tossing a penny onto the board. Take as many paperclips (or other small objects) as the number your penny lands on. Count your paperclips after 2 tosses to see who won.

5. Exponential penny toss – this is something that I saw here. It’s not exactly for little children, but I can’t imagine a 5-year old NOT having fun with an experiment where his parents actually ASK him to toss 100 pennies.

6. Since we’ve been talking about different geometric shapes lately (thanks to The Greedy Triangle book), we might try to see how many of the shapes can we build with 10 pennies. How about 20 pennies?