Coin Problem Solving

Problem 1:

How many new 20 cent coins would be needed to make a coin trail from one side of your classroom to the other?

Problem 2:

Would one million new 10 cent coins fit into this classroom?

Problem 3:

How many new 50 cent coins would be equal to your weight?

Problem 4:

How many stacked $1 coins is the same height as you?

Problem 5:

How many $2 coins will cover the top of your desk with no coins overlapping and as few gaps as possible?

Problem 6:

Write some other problems like the ones above and work them out yourself or challenge others in your class to solve them.

Teachers' Notes:

These problems are designed to get students thinking. It is likely that students will need time to think about how to solve them. A class discussion may be needed on ways to solve problems like these. Leaving students to test ideas is part of problem solving therefore the teacher is encouraged to give suggestions and help sparingly.

'Simplify the problem' is a good problem solving strategy for students to consider when working out these problems. For example, simplifying the first problem by first working out how many 20 cent coins for the length of a book or for 10 cm. Working out the length of 10 coins is another way to start. Once this is known, use this information to work out longer lengths as in the table below.

Changing the distance, weight, height or coins in these problems will change their difficulty. It may be better to start with a smaller or shorter object to measure for some students. More able students could be challenged to measure objects not horizontal or straight. Older or more able students need be encouraged to think of alternative ways of working the problems out rather than by simply placing and counting coins.

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