ask him to show you the one he thinks you "plagiarized" and then when it doesn't look like your's take it to the school board.

FYL I would love to know what myth you did OP. The teacher is probs just being an ass-hat. Plus its really difficult to invent a myth for a natural disaster because they have all been done before. Just study the religions of Greece and Rome and you'll find that. I think your teacher is asking a little too much.

To be fair, I can't remember what the phenomenon is called, but you could have read it somewhere originally and while it is your own story, it could have elements of the original one that you've subconsciously written in.

It happened to me a decade ago. I had what I thought was an original idea for a fantasy-dystopian novel, and I've started to write it, without ever talking about it with anyone. Some months later a guy of a fantasy forum wrote a short story wich ambientation and plot were basically identical to mine. The worst part? Half of the comments said it was a rip off of a famous novel I never heard before. The other half just said that the idea sucked. Ouch.

damn that sucks

Simpsons did it

Maybe you should have researched your own story more to make sure it was truly original.

"There are no new ideas. There are only new ways of making them felt." - Audre Lorde "There is no such thing as a new idea. It is impossible. We simply take a lot of old ideas and put them into a sort of mental kaleidoscope. We give them a turn and they make new and curious combinations. We keep on turning and making new combinations indefinitely; but they are the same old pieces of colored glass that have been in use through all the ages." - Mark Twain, a Biography "What has been will be again, what has been done will be done again; there is nothing new under the sun." -Ecclesiastes 1:9

Show him the original story. It's a little more believable when you have proof.

Reusing your old work and presenting it as new is even more intellectually dishonest than plagiarism. I'm guessing your "original" story is based on a classic myth that you read and forgot about.