Cat Ransom

Cat Ransom

Starting Point


Your elderly neighbour has just approached you for help.  She is upset.  Her cat, of whom she is very fond, has disappeared.  She has received a ransom note asking for $1000000 in circulated $5 notes.  She only has a few hundred dollars but wants her cat back and is asking for your help.

She has the idea of cutting paper to the right size and putting it in bundles with a $5 note on top of each.  Can you help her get it all ready?

The Big Question

How big will the bag need to be to carry it all to the ransom drop?  And How heavy will it be?


I had a lot of fun running this with a class.  We started with my small carry-on bag and they speculated about how many books they could fit in it.

I then gave them the scenario and showed a couple of $5 notes.  I had guillotined some plain paper into the right size and had a few piles of that as well to produce later (only about 40 sheets of paper cut up).  I asked them for suggestions of what to do.  They suggested cutting some paper to the right size first.  They also said it would take a long time to cut enough paper.  They worked in pairs at first but later some of those pairs merged to form groups of four.  Their first task was to measure the note and cut some paper to the right size.  I then produced my pre-cut paper and asked them for suggestions of how to decide the size of the bag. 

They suggested measuring the size of a bundle then working out how many bundles they would need so I sent them off to work on it, reminding them that they also needed to find the weight.  We had some scales on the table now as well. 

This needs a very long period or two periods as there is a lot for them to think about and to do.  The class finished with groups sharing their findings and how they had gone about it.

Try it.  You may be surprised at the answers – the students certainly were.

(Grades 5-8 – measurement – length, volume of a cuboid, mass – problem solving)

[contributed by Marj Horne, Community Leader]

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