BIG QUESTION

I am dashing into school after a meeting this morning when one of my first grade friends stops me in the hall. "Ms. Carol," he says, "you know how we have been talking about cumulative stories?" I do know, but I am surprised at his question, because we actually talked about cumulative stories several months ago. 

While I get my bearings in the conversation my first grade friend continues, "Well you know how in cumulative stories, things get more and more and more? Yesterday, we read the Eric Carle study about the rooster off to see the world. And things get less and less and less. So what is that called?"

It's a great question. I can think of stories like TEN IN THE BED and FIVE LITTLE MONKEYS where that happens, but I truly don't know what it's called. I promise T that I will try to find out and go on my merry way through a very hectic day, promptly forgetting my promise. After school, T approaches me on the playground. "So did you find out?" he asks. I tell him that I haven't yet, but I will work on it tonight. 

T looks a little dubious, "Well if you don't know," he says, squinting up at me, "Do you think you could ask a fifth grade teacher?"  I assure him that I will, and after school I go and ask Rob, who teaches fifth grade, and is probably much smarter than I am. Unfortunately,  he doesn't know either. I also put it out on Twitter. And now I'm posting it here. Does anyone know the answer? What do you call a story where things get less and less and less?