Hand it to them
Fill a rubber glove with water and freeze. Just think of all of the questions that children could ask, from: "How can we stop it melting?" to "Why are some parts of the ice hand transparent and others not?"
Extend children's experience of changes of state by freezing different substances. They often want to make their own ice hands using a range of substances, from soft drinks, jelly, custard and wood shavings to cooking oil, tomato sauce and milk. One child whose mum had just given birth wanted to see what would happen to the contents of the baby's nappy if frozen. Do let them try out their ideas, within reason.
Freezing baked beans can be used to help explain what happens to water molecules when frozen and the reverse change when thawed. The beans are close together in the frozen hand and then as the bean ice hand thaws the beans (particles) move apart.
It is a shame that this model doesn't work for evaporation as well, but ice hands still have a lot to offer scince*
Rosemary Feasey is a primary science consultant