Let the child
The main thing to salt one of cubes.
Let the child will attentively observe how influence cheese, rice, pepper, fennel and salt on ice.
What of cubes thaws quicker?
The salty cube, of course, will thaw before others.
It will be the first discovery in your laboratory.
Now we learn how corn flakes influence ice thawing speed, millet and grain crumbs.
Perhaps, the child will find out, than it is necessary to strew paths in the winter that also ice on them thawed, and birds were fed..