At the end of the story, Charlie returns by mistake to his old class with Miss Kinnian. He is again mentally handicapped and temporarily forgets that he had an operation that made him much more intelligent. He forgets that he left the night school.
When Miss Kinnian sees him sitting back in her classroom as if nothing has happened, she runs from the room crying. It breaks her heart to see Charlie in his old state after he had come so very far intellectually. In addition, when he was highly intelligent, Charlie and Miss Kinnian had dated and started to fall in love. Charlie doesn't remember this, but Miss Kinnian must be heartsick to think a man she might have built a life with is now once again in a childlike and dependent state.
Charlie describes the scene as follows in his journal:
She startid to cry and run out of the room and everybody looked at me and I saw they wasnt the same pepul who used to be in my class.
Then all of a suddin I remembered some things about the operashun and me getting smart and I said holy smoke I reely pulled a Charlie Gordon that time. I went away before she come back to the room.