I just got through going over the alphabet with Knuckles. He knows every capital letter except for W and X (he thinks X is K and he keeps turning W upside down and calling it an M).
I can't believe this kid. He just adores letters. You can't stop him from finding them everywhere. He opens up random books and points out the letters he recognizes. He even knows the first few letters in his name, so he can spot when his name is on something.