What's with the letters?

Maddox is crazy about letters right now! All he wants to do is talk about letters. He now knows O, B, R, and almost has K & X but still gets them mixed up sometimes because let's face it they look almost the same. This is all him. I will tell you that he hates the letter W. I don't know why, but he doesn't want to admit that it's even part of the alphabet. What I really don't get is that we talk about letters for three days and he already knows at least three of them, but we've been talking about colors for a while now and he still tells me that every color is blue.