My kids never learned sight words (obviously they learned them but I never taught them). So many schools push flash cards so hard and I've never really understood that. Kids can easily learn sight words just by seeing them over and over again in text.
With DS, I printed out a list of Dolch sight words one day to see if he knew any of them, and I was shocked he could read almost all of them. He was probably 4. This was after he learned how to blend words but before he really started reading frequently (we were at the stage where I occasionally tried to get him to read a BOB book or something similar to me).
