Everyone should be a teacher at some point in their lives. I don’t mean, of course, that everyone should be a paid teacher in a public school. There are far too many hoops to jump through for that. But in teaching your subject matter, you sometimes discover new truths about it. You’re forced to, when you have to explain your choices to people who haven’t yet developed the unconscious competence that you’ve absorbed through years of trial and error.

This semester, I got to teach about 33 high-school seniors the basics of short story writing. Among other things, I did expose them to a whole list of handy “don’ts.” Don’t switch viewpoints if you can avoid it. Don’t write in both past and present tense at the same time. Don’t end your story with “And then they woke up and it had all been a dream.”

Of course, these being high-schoolers, I got ignored a lot. Having taught high school for years, I am well aware of their tendency to do whatever is easiest, besides the permanent streak of “you can’t make me care” that is natural to the age. But I didn’t expect to get so much apparent pushback on that last one. I had stories that ended when the main character woke up. I had stories that ended when the main character got dragged away to an insane asylum. Or back to their cell because they were already in an insane asylum. Or won what turned out to be a game.

And I realized then that this wasn’t pushback at all: this was the desperation of people who didn’t know what to do to end their stories, and hadn’t seen the common thread that was so obvious to me. Many of my readers will have figured it out already, but for those who aren’t to where they can do that yet (and we all pass through that stage), I’ll spell it out: the problem with all of these endings is that they destroy the actual story.

How do they destroy it? Well it helps, perhaps, to think of a story as a game. A game played for stakes. When you read a story, the characters’ lives, fortunes, their sacred honor, even their souls may be at stake. If it’s at stake, that means they can be lost. When the events of the story are revealed to be a dream, a hallucination, or a game, then that means none of it was ever really at stake in the first place. It’s like discovering that the players around the poker table, wagering thousands of dollars, were in fact playing with Monopoly money.

So I had to break that down for them, and it was interesting to watch the lights go on. And there are even ways around these endings that can make them meaningful. A Christmas Carol ends with Scrooge waking up, but you never doubt that his soul was really at stake and that the Ghosts were real. Shutter Island does indeed end with Leo DiCaprio’s character being dragged off to the insane asylum, but it works because he did have a moment of understanding in which he could have chosen the hard road back up to sanity, rather than embracing his delusions. In Larry Niven’s and Steven Barnes’s Dream Park, the game matters because a) the characters are well-defined enough that the game has real-world meaning to them, besides being entangled with an actual murder. The problem with these endings, most of the time, is that the writer confuses emotion with stakes.

We’ve all been really scared by a bad dream. The fear is real. And certainly, the plight of someone suffering through insanity (or even mental illness) is heart-wrenching. But watching someone be scared by a bad dream, or someone be insane, or someone be thrilled by a game is not interesting. That’s like watching an injured athlete sit on the sidelines. It may be very sad that he is there, but it’s not going to change for the whole game. He has no role to play in it, and he will be lucky to get two sentences said about him for thirty seconds of screen time.

You can tell a meaningful story only if the dream, the insanity, or the game have real meaning in the characters’ real lives. Anything less, and the readers have no reasons to care