Sometimes it's hard to know exactly what JT knows and understands.
Yesterday we were in the kitchen, and there's a billion magnet letters on there. He's been messing with them since I found them Saturday night, organizing them in his own way and naming them.
I know he knows the majority of upper case letters (actually, as far as I know, he knows all of them). Some of the magnets on the fridge are lower case, aka "baby letters".
Surprisingly, he looked at the lower case b, and said "B".
I had no clue he knew any baby letters (besides the ones that look just like the big ones).