Erin shatters a jelly worm
Erin is 13 and helped me to teach some of the younger children about what happens to flexible things when you cool them down.
First we took a jelly worm and pulled and prodded it to see how it felt. At room temperature it was flexible, squishy and stretchy and some of us could tie them in a knot!
Erin hit one of the worms with a hammer, but nothing really happened to it, and any part of it that was squashed initally from the force, sprung back out to its original shape after a few seconds.
Then I took Erin's worm and dipped it in dry ice which cooled it down to -78C, I then gave Erin back her worm and when she hit it with a hammer it shattered into little pieces!
We then all scrambled to find the pieces and eat them as quick as we could, so they were crunchy in our mouths, it we waited too long they warmed up and went back to being squishy.
The reason why the worms went from squishy to brittle (where they shatter) was because we cooled them to below their glass transition temperature which is the temperature where the atomic chains can move in a flexible manner. Without the flexibility of the chains, the atoms can't move around the force of the hammer and so instead the chains break. This is what we call the ductile (squishy) to brittle (easily shatters) transition temperature.