Try to convince the teacher to give you an assignment that you're confident you're going to succeed in.

The first thing you want to do is get the basic outline of the story. Just steal one from something you enjoyed. If your hero is male, is he going to have to kill a dragon to rescue a girl? So you need to think about the main points: how does the hero know about the girl in the first place; where is she being held; how is the dragon guarding her; how is the hero going to defeat it. Once you've thought of or better yet stolen a basic storyline, you need to divide it into three parts. Spend the first part describing the environment, the characters, and the situation. Imagine the place where the hero and the girl live and describe it. Imagine what the characters are like and describe them: use real people and places as a guide. If you're really good at characterisation, this is also where you'd make the hero likable and the villain not. Part 2 is where the bad guy ruins the good guy's life in some way, and appears to have the upper hand. Really give the good people we like a shitty time. Part 3 is where you have the people we're rooting for triumph and everyone lives happily ever after. Of course, if you want to write something original and interesting, don't do any of this, but if you just want to bang out something for English class...

At 3, unless that teacher is either high as fuck, or the OP is lucky enough to go to a really progressive school, I highly doubt that idea will work. You don't get alternate assignments just because they're haaaaaard. You do your homework like everyone else or suffer the consequences. Now, personally, I think homework is a sham, and the educational system in America, at least, has gone so far off the rails that it's long been a raging, fiery wreck that everyone from politicians to parents to students themselves are too intimidated to tame, but one person making a stand and saying they want a different assignment isn't going to do a lot. By all means, ask for help, as you've done here. but don't expect miracles. If that were a real thing, I bet 99% of kids wouldn't take math classes.

Write it like you're writing a fanfiction, with characters you already know you enjoy and that can help you get the juices flowing.  When you've written the fanfiction, then pull out the names of characters that are form the game, anime, whatever you used and make up original character names.  Tons of authors have done this, and it defs helps with writers block for churning out a quick assignment which really 3 pages would probably be about the length of a 1 shot in fanfic circles.

I'm not sure what in america a ""sa" is but frankly I'd have loved an assignment like that.
I've always personally loved making up my own stories, and now am writing myself regularly so I'm probably not the person to give advice.

However, if writing isn't your thing that's fair enough, though unfortunately in this instance it sounds like you need to have a crack at it anyway.

One of the fundamentally basic rules for a story, (and one of the differences between a story and a poem), is that a story has to have plot.
You have to have things one way at the start of a story, and another way at the end, so my advice would be to first decide on where your setting your story, who your protagonist is, and what thing is going to change in the course of the story.

I'd personally suggest steering clear of huge plots that require lots of time space and character, including the generic kidnapped girl/romance angle, or world distroying villains, since you probably don't have the time or inclination to write them in enough detail to be effective, EG unless you have something interesting to do with the kidnapped girl or can write a convincing relationship, just having her as rescue bate probably wouldn't work.
Just go with something simple, EG a single monster encounter if its a typical fantasy, an encounter with a single type of alien if its an sf story, a single bit of mangling if its a time travel story etc.

You don't even have to go with the idea of a villain or obstacle at all, maybe its about someone who realises something about themselves, or learns something that changes them.
One of the finest short stories ever written Shirly Jackson's "the Lottery" is simply about the lottery of the title,  very disturbing ritual carried on in a small village, and its only at the end you realise the rather worrying point of this ritual

Once you've decided what your basic idea for the story is, your central premise, then decide where the start point is, and where the end point is, with a vague idea of how you get from one to the other.
EG, you begin with the couple driving into the creepy town, then you know your going to end with the bed in their hotel room growing teeth and munching them both up, or you begin with the knight riding up the cliff to fight the dragon and rescue the princess, and know your going to end with the fact that the princess was actually a sorceress who was in command of the dragon all the time.

Once you know where your starting and where your ending, then basically all you need to do is connect the dots.

This is what I tend to do, I have a vague idea of where things are going and then I just splurge! then I check through many times.

hth.

I have a similar issue myself Mata as regards depression.

What I've been doing over the past few days is taking some advice from Stephen King.
He writes 1000 words a day. It doesn't matter if its crap, it doesn't matter if it doesn't make sense. He writes because the act of writing is itself cathartic and helps to get creativity moving.

I've not quite managed 1000 yet myself, usually more like between 500 and 800, but I have a story (actually a short story/novella), and its coming together. Admittedly I have the advantage of having just finished a phd, and not! having to write about ethical concepts of disability and be able to write about weerd aliens instead is  more fun .

One major issue I do have is wondering whether my writing is any good, whether I@m just talking crap and giving up in disgust. This is a real problem and I've only found two ways around it.
First, I have a very intelligent and honest wife who is more than happy to read what I write and tell me what she thinks I need to fix. She already does this with my book reviews and has started doing it with my story too.

Second, recently I read a really! really! crappy book. (if anyone is wondering it was Mort(e) by Robert Repino).

It was honestly one of the cruddiest things I've ever read. Opinionated, slow, depressing, with a deus ex ending, characters who were utterly dislikeable, ----- the review should be appearing on fantasybookreview.co.uk soon.

Whenever I start to get that sense of "Oh this is so crap!" I go and reread my review of that book over again and remember how aweful it was. And this guy is a published author!

However cruddy my writing is, I can be fairly sure that its not that! bad .

The other thing of course, is more happily I discover interesting things whilst writing which I didn't think of putting in their at all.
Tad williams once spoke about "ideas that just sit on the page and be intresting"

Even though I'm scarcely four k words in thus far, I've already run into several of these, which is really exhilarating.

Well its supposed to be written essay, this is what the lack of braille does to blind people.

I don't get your point, Ironcross. What does lack of braille have to do with writing essay?

@17 you kinda proved my point for me, although I'll admit I didn't even notice it until Dark mentioned it. It was written SA, (sierra alpha) rather than essay (echo, sierra, sierra, alpha, yankee). This is what happens when blind people don't learn braille, they have a fundamental lack of the knowledge of spelling in the English language which causes these things to happen. They themselves don't realize the problems that poor spelling can create for them. Especially the teens, but they will have to face up to some hard realities when it comes time for them to go to college, or try to enter the workforce. Papers will come back with marks all over, résumés will get chucked.

As regards perfection Mata, one thing I'm realizing is that its far more important to just sit down and bloody write than to try and constantly agonise over what! to write, since the more writing you do, the easier it is to get into the habit of doing it, and starting is always  than trying to tidy something up you've already written.

I've often found this with my book reviews, I'll be stuck on how to start or how to put the points in order I want to make, then if I just sit down and force myself to splurge suddenly everything seems to just come together.
Its not easy but in the end its rewarding to be able to do it.

well this may sound really stupid and crappy and coming from a disney movie, but I know what I'm talking about here, sometimes I'll sit down and write more then 1500 or 2000 words in a couple hours. but on with the point. what I do is a afew things. one is make music. it always helps me come up with ideas. from 8bit music with barely a beat to intense battle music, it puts ideas in my mind, and then all of a sudden I want to go write something. or, you could, take my advice, it, works, just sit down, and imagine. don't think real. think like you are not even existant in real life, you're somebody else living in a different world, in the past or future. it could be anything. that, although it may sound stupid, will give you a iojvkbviorueowirlkjsdfghjhhjasforuowieqpr amount of ideas. huge amounts. I'm writing a novel, its up to like 30 pages now, and that is because I sat down one night on the chair, watched some tv, made some music and thought. just write whatever comes to you. you'll then get used to it and be able to make ideas much easier, they'll sort of just start coming to you all the time like rain. well there's my advice, hope you get some use out of it.