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To Be Salty Sea Ice Or Not To Be Salty Sea Ice
An Introduction To Sea Ice At The Polar Regions

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Dr. Martin Jeffries, one of the world’s foremost authorities on polar oceans, told this story.

Dr. Martin Jeffries, Research Professor of Geophysics, Geophysical Institute, University of Alaska, Fairbanks

“When I was young, 7 or 8, a child in Manchester, England, I saw the headline and photo in our newspaper, Sea at Brighton Freezes Over. This was astounding to me. Brighton is a seaside resort in the south of England. Surely they were mistaken! How could the sea freeze? It was so salty!”

Was he right to be amazed as a child? Was he correct that a frozen sea at Brighton (or anywhere else) was impossible? Was the newspaper right? Can briny, salty, sea water freeze?

Can you design an experiment which shows whether or not this could have actually happened?

What do you need to carry out your experiment?

This is a list of materials already in the classroom:

  • Clear plastic cups, paper cups, popsicle trays, ice cube trays.
  • Salt.
  • Distilled water.

    Let the teacher know if you need anything else for your experiment.

    Can sea water freeze?

    Using your choice of materials from the above list, design an experiment to determine if salt keeps seawater from freezing.

    You will be expected to journal (write and/or draw):

  • Predictions.
  • Experiment plan.
  • Observations.
  • Conclusions and explanations.
  • An evaluation of your results.

    Use a visual to share your findings with the class.

    Discussions Questions/Extensions ......

  • After seeing the results of your experiment and you classmates’ experiments, would you predict that it is possible to put so much salt in water that no matter how cold it gets the water won’t freeze?
  • What else could you try in water other than salt to see its effect on freezing? You must check with the teacher before trying any new experiments.
  • How much salt is dissolved in ocean water? Do you think it is the same worldwide? How about near where rivers enter the ocean, or in oceans near deserts where there is a lot of evaporation?
  • Find out if the ice in your cups is salty or fresh.

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