Other than his spelling/writing improving, what are some other examples of Charlie's improving intelligence?

Charlie learns the way things work at the bakery, and when the guys try to play a prank on him by asking him to mix the dough.... he ends up with a promotion.... to "dough mixer".

Another example of his improving intelligence is his loss of innocence. he no longer does things just because he is asked, and he no longer wants anyone to read his journal. Charlie's loss of innocence has caused him to become questioning.... suspicious.