My boys love a challenge, like "Lift this ice cube without touching it." When I handed them some lengths of embroidery thread and told them to pick up ice cubes hands free, they gave it their best try. But, of course, it was impossible.
Or is it?
Next I had them lay the lengths of thread over each cube so that there were ends overhanging on each side. Then they added salt, completely covering the thread and cube.
And then we waited (about 3 to 4 minutes).
When three or four minutes had passed, I told them to pick up both ends of the thread. Much to their surprise, the ice cube came with it!
We talked about how it worked and my 10-year-old came REALLY close to figuring it out.
Why it Works
The salt melts the ice slightly but then it refreezes. Salt water has at a lower melting point than water. This process traps the thread on the surface of the ice cube, thus making it possible to lift it easily!
This wonderful idea came from The Everything Kids' Magical Science Experiments Book by Tom Robinson. It's filled with page after page of extraordinary science activities!