Take five glasses of water. Leave one plain water, add one tablespoon of salt to the second glass, two tablespoons of salt to the third glass, three tablespoons of salt to the fourth glass, and four tablespoons of salt to the fifth glass. The fifth glass will be about as salty as the Antarctic Ocean, the saltiest ocean on Earth.
Can you predict which one will freeze first? Put them all in a freezer and take their temperatures every 15 minutes. Graph how long each one takes to freeze and what their temperatures are each time you measure.
In many parts of the world, road crews sprinkle salt on the roads during the winter. Why do you think they do that? How would it help?
Yet another project with ice
More about ice
More about temperatures
Bibliography and further reading about ice: