There is a very old fable about a crow and a partially-filled pitcher of water. Here is a modern retelling of the story, taken from an advertisement for Birla Sun Life, an Indian investment company.

Today you get to play the part of the crow! Brainstorm a few ideas to get to the water – you are a thirsty crow!

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Here’s what the crow decided to do:

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How many pebbles does the crow need?

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Activity:

Gather your supplies: a cylindrical jar or glass filled about half-way, six stones, a ruler, paper for noting water heights, a GeoGebra Applet.

1. Measure the height of the jar and subtract 2 centimeters – that’s the level the crow needs to be able to reach the water.
2. Measure the height of the water in the jar and record it.
3. One by one, add stones to the water, recording the height of the water after each addition.
4. Stop and make a prediction. How many more does he need to add?

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Analysis:

Explore the problem with Desmos on your iPad.

Download (PDF, 2.25MB)