I'm going to guess that the black ones will grow up to be Barred Rocks, The white ones could be White Rocks or White Leghorns, and the grey one....Well, I'm not sure. Does it have feathered legs?
The black ones look like Barred Rocks. The white ones might be white leghorns. And the grey one, I was thinking maybe Blue Andalusians, but now I'm not so sure...