Children's book: The black hole

Astronomers say that a black hole can be much bigger than you can imagine. What do we know about black holes who know nothing about the concept of a black hole developed by the German astronomer Karl Schwarzschild in 1916 on the basis of Albert Einstein's theory of relativity? The same thing that any child would know: that they are very large black holes, that they were smaller in the beginning, but that they can be blacker and bigger than you imagine. And it is already known that, put to imagine, children give us a thousand turns.