Cold Evidence
A woman returning from a few days’ trip checked that the freezer was cooling normally and that the food she had stored there was frozen.
Still, when she saw the ice in the clear container, she decided to throw out the food just to be safe.
The container held nothing but water, and no one had entered the house while she was away. What did she figure out?
Let’s unravel your preconceptions, one by one.
View Hints
3 Levels of Hints
Take it little by little, just as much as you need.
Hint 1
The woman wasn’t just concerned about the temperature at the exact moment she returned home.
Hint 2
The shape of the ice was different before she left than when she returned home.
Hint 3
Even if no one moved the container, the shape can change once the water inside turns to liquid.
Check the Answer
The truth behind this mystery
Before her trip, the woman had tilted the clear container with a lid slightly and let the water freeze in that position. She then returned the container to a horizontal position and placed it in the freezer.
The ice had settled evenly across the entire bottom of the container and was shaped so it wouldn’t roll around. When she left, the top surface of the ice was slanted.
However, by the time she returned home, the top surface was level. While she was away, the freezer had temporarily stopped cooling; the ice had melted and then refrozen inside the level container.
Although the food was frozen now, she didn’t know how warm it had gotten at some point. Worried about this, she decided to throw it away just to be safe.
If you notice this, you’ve got it right
From the change in the ice’s shape, she realized it had melted and refrozen while she was away, and she worried that the food might have warmed up temporarily as well.
There’s no need to guess whether it was a power outage or a malfunction, or how many hours it lasted. Even with ice of a different shape, the answer is correct as long as the mechanism allows you to detect melting and refreezing. The changes in the ice alone did not reveal the extent to which the food had spoiled.
Suggested questions and answers for group play
- Was the freezer cold when she got home?
- Yes.
- Were there any thermometers or electronic devices inside the container?
- No.
- Did the color or smell of the ice change?
- No.
- Was the shape of the ice different from before she left?
- Yes.
- Before leaving, did she freeze the water with the container tilted?
- Yes.
- Did she then place the container horizontally before leaving?
- Yes.
- Did the ice just roll around inside the container?
- No.
- Did the ice melt and refreeze while she was away?
- Yes.
- Could the food have warmed up while she was away, even though it was frozen when she returned?
- Yes.
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