Mathematical Problem Solving – Coin Puzzle

Problem Solving Activity – Blow a Coin over a glass – This classic problem provides a lot of opportunity for the exploration of variables.


Mathematical Problem Solving

Coin Puzzle

Problem Solving Activities

Problem Solving Activity

Task – Using only your breath you must blow the coin so that it goes over the top of the glass ie it doesn’t land in the glass or on the table.

You may not touch the glass or coin and you may use nothing but your breath.


– a large glass or a plastic cup
– a small coin – (5 cents/nickel)


1. Set the coin and cup up on a table so that your whole group can see it.
2. Balance the coin on the edge of the glass.
3. Outline the task to your students (or drinking buddies).
4. Ask for victims/volunteers to come up and have a go at blowing the coin across the top of the glass.
5. Children break into pairs with their own equipment to solve the problem.

Hints to Lead Students to a Solution:

– The task is not impossible. It can be done!
– Perseverance is needed!
– Frustration will probably occur.
– If someone whines, ‘I can’t do it’ get them to add the word ‘yet’ to the end of the statement.
– Insist the students must discover the secret of the task and be able to replicate it.
– After a while, draw a diagram showing the direction of air coming from your mouth.
– Brainstorm variables e.g. how you hold your lips, force of air coming out of your mouth, where to blow & where not to blow.
– Encourage the children to have their parents do the task.
– Get the kids to use their own coins so your’s don’t disappear 😉

Teachable Moments / Discussions to Have:

– Seize the ‘a-ha’ moments, celebrate and discuss them.
– Life is hard but you will not succeed if you give up.
– The mark of a person is what they do after they fail for the 4th, 5th & 6th times.
– Think problems through. What can I do differently this time?