No, it wasn't a school assignment. I hope they don't have such books on a mandatory reading list today. [Though with this crew at the helm you never know.] I do not recall how I came across this book. But I was ready to graduate from the university by 1984, so my psyche could not be severely damaged - not after the course in electrodynamics :-) As matter of fact, some of Kafka's stories (like The Metamorphosis or In the Penal Colony) were far more disturbing; perhaps because I read them earlier.
I have hated the very idea of The Metamophosis, since high school around 1973. I refused to finish the book, and wrote a bio on Edgar Allen Poe instead. Meta made my skin crawl. I guess that means he was a good writer, to have such an effect without using one word of profanity.