Puppy development

I am reading a book on dogs by Amanda O'Neill.  For the first two weeks of life, puppies do little but sleep and feed.  By about three weeks, most pups have started to take an interest in life and each other.  When they learn to play, at about four weeks, they are starting their schooling--learning how to be a dogs.  By about 12 weeks most puppies are able to join grown-up games.