Measuring Money: Coins

The newspapers are full of talk about the money supply, printing more dollars, interest rates,  foreign exchange, etc. That's high-level finance.

But in contrast, today I'm looking at low-level finance. Pennies and nickels and dimes, and the units of measure we at Excel Math employ as we teach kids about metal money. Actually, we don't care that much about the value of the cash.

What? What is there to worry about if you don't care about the value of the money? What do you teach kids - which face is on which coin?

Yes, we teach which face is on which coin. But forget that - today I'm not talking about which President's face is on which coin, I'm talking about the other physical characteristics of the money:

In this one image I have combined the absolute and relative size (diameter, thickness) of coins, their characteristics (ribbed or smooth), the material they are made of, and their weight. We use this information in some Excel Math lessons and activities. Kids can do lots of calculations using units of measure and value - and they like working with something they can put into their pockets.

What adult would care about these things?

These adults care about the physical units of money measurement:

• manufacturers of coin-counting or change-making machines, who decide if a coin is legit
• bus, trolley and train operators, whose vehicles get filled with coins during a route 
• drivers of armored cars, who move money around (it's called "cash in transit" service)

• prospectors, who have to deal with the weight of nuggets and bullion
• the mint, the folks who make and sell us these coins
• vending machine operators, who collect money we've dropped into their machines

If any of our Excel Math students end up in a job hauling money around, they will be prepared.

Tomorrow we will investigate the dimensions of paper money.