If the table is based on two eggs, one of which is raw and the other cooked, how can this be determined? Of course, every woman will do it with ease, but to show the experience of the child - it will be interesting.
Of course, it is unlikely to connect this phenomenon with the center of gravity. Explain to him that the cooked egg center of gravity is constant, so it is spinning. And raw egg inside the liquid mass is like a brake, so a raw egg can not be twisted.