Theory:

Patrick got his A’s; his classmates were amazed; his teachers smiled and were full of praise. And his parents  wondered what had happened to Patrick? He was now the model kid who cleaned his room, did his chores, was cheerful, never rude, like he had developed a whole new attitude.
Explanation:

Patrick scored "A" grade. His classmates  were startled, teachers were full of admiration and parents were trying to know what made him so good, what had transpired him? He became an ideal child who cleaned his room himself, did all his work, became a  wonderful child who was never rude and developed a completely new self.
 
Meanings of difficult words:
 
Numbers
Word
Meaning
 1.
Kid
A child chores: work that must be done everyday, often boring.
2.
Attitude
A feeling about someone or something.
3.
Amazed
Surprised.
Reference:
National Council of Educational Research and Training (2006). Honeysuckle. Who did Patrick's Homework - Carol Moore (pp. 7-10). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.