What you need:
An ice cube
About 20cm of thin wire
Two equal weights eg full drinks bottles
A sturdy piece of wood and a brick
In a cold room, weight the wood down on a table with the brick. Let the end jut over the edge and put a slab of polystyrene on it.
Fix the weights to each end of the wire – use strong tape if necessary.
Hang the wire over the middle of the ice cube. Wait for some time. The wire should cut its way through the ice but leave the ice cube in one piece.
Results & explanation
Because ice is less dense than water, pressure from the wire squeezes and helps to melt it. (Scientists are still trying to understand all the reasons why it melts!) As the wire moves down, the water refreezes above it.
PS – Marvin & Milo are © IOP and can be freely used in schools. Please do get in touch if you’d like to modify or use them for commercial purposes.