Coins and bills

Pennies, nickels, dimes, quarters and one-, five- and ten-dollar bills to put on the table, count on from the biggest, trade for smaller pieces and build to an amount.

How to use it

Press a value in the tray, or P, N, D or Q on the keyboard, to put a coin or bill on the table. Pieces sort themselves from the biggest to the smallest.
Press Count on (C) to step through the pieces from the biggest, with the running total shown each time. Tap a piece and press Trade it for smaller to swap a quarter for dimes and a nickel.
Press Give me an amount, choose To 50¢, To $1 or To $5, build it from the tray and press Check it. The answer says whether you used the fewest pieces.

Ideas for class

Put out a quarter, two dimes and three pennies and count on together: twenty-five, thirty-five, forty-five, forty-six, forty-seven, forty-eight. Ask what changed when you moved from quarters to dimes.
Ask for 40¢ in as many ways as the class can find, then ask for the way that uses the fewest pieces. Check each against the total.
Trade a dollar for four quarters and then each quarter for two dimes and a nickel, and ask if the total ever changed.
Give an amount to build and ask students to show it on whiteboards first, then check with the tool and talk about any difference.
Put out one of each coin and ask students to put them in order by value, then in order by size, and talk about why the two orders differ.
Use the To $5 level for a shopping routine: build the price of an item, then build the payment, then ask what change is needed.
Count a pile of pennies to ten, then trade ten pennies for a dime in two steps using nickels, to show why ten cents is both.

Questions

Why do the coins not look like real money?

They are plain circles and rectangles with the value in large type. Real coins carry portraits and small print that cannot be read from the back of a classroom, and plain shapes keep attention on the amount.

What are the trades the tool offers?

A nickel for five pennies, a dime for two nickels, a quarter for two dimes and a nickel, a dollar for four quarters, a five for five dollars and a ten for two fives. They are the usual classroom swaps.

How does it decide the fewest pieces?

By taking the biggest piece that still fits, over and over. For US coins and bills this always gives the fewest pieces, which is why a quarter, a dime and a penny is the answer for 36¢.

Is there a limit to how many pieces I can add?

Thirty on the table at once, so every piece stays large enough to read on a projector. Clear the table with R to start again.

Does it keep anything about what students build?

No. The table and the amounts live on the page until you close it, and nothing is stored or sent. There is no score and no record of who answered what.

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Using the money tool in class

Money is the everyday use of place value and skip counting. Students who count 25, 50, 75 and then 85 and 86 are using the same skills as in a number line, with value attached to each piece. The tool counts from the biggest piece down, which is how children should count, so every count shows the running total.

Begin with pennies and nickels only, and count by fives and ones.
Add dimes, then quarters, always counting from the biggest.
Introduce trading as a way to make the same amount with fewer pieces.
Then move to dollar bills, and to amounts with dollars and cents.

Common mistakes

Counting every coin as one cent, so that a quarter is counted as 1. Say its value before you move it.
Counting the pieces in the order they were placed, which makes the running totals jump. Always count from the biggest.
Thinking a bigger coin is worth more because it is bigger: a dime is smaller than a penny and worth more.