Monday, September 20, 2010

Coin Combinations

It is important that students recognize that there are often different combinations of coins for any  particular value.  Many problem-solving activities incorporate this skill as students search for all of the different ways to make 50 cents, for example.

One teacher uses these large coin cut-outs, available at teacher supply stores, to challenge students to find different combinations for the same value.  The students love being at the board, manipulating the large coins,  and coming up with different combinations.  Students at their seats work with small bags of coins to complete the same task.

Consider adding this station to the daily math routines.  Challenge students to find many different coin combinations for the date.  Repeated practice in the primary grades would help build flexibility with coin combinations, an important skill in counting coins and making change.

Teachers might use A Quarter from the Tooth Fairy as an introduction to the concept of coin combinations. 

In this book, Caren Holtzman [Hello Math Reader, Level 3] recounts in verse how a young boy spends the quarter he got from the Tooth Fairy for his tooth.   He first buys a monster for his quarter but then decides it wasn't quite right and returns it, getting 2 dimes and 1 nickel back. 

Each time he buys and returns an item, he gets his 25 cents back in a different combination of coins, making this book an excellent introduction to the problem of how many different ways students can make 25 cents.

Challenge:  Try to find all of the different ways to make 25 cents with coins.  Students may use the Student Worksheet to keep track of all of the different ways.

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