How is the operation a second chance for Charlie?

The operation gave Charlie a second chance to be smart. He gets the idea for 2nd chances from Miss. Kinnian.

I hope they use me becaus Miss Kinnian says mabye they can make me smart. I want to be smart.

I told him thanks doc you wont be sorry for giving me my 2nd chance like Miss Kinnian says. And I 'meen it like I tolld them. After the operashun Im gonna try to be smart. Im gonna try awful hard.