SOLVED. Teacher whose students are shapeshifters [s]

[Becca]

Warning- this will include a spoiler.

I'm almost positive I read this book/short story in middle school or early high school (late 90's, early 2000's). It involves an older woman who has been a teacher for years. She was going to retire, but then decided to stick around for another year. From years of teaching she's learned a few tricks, such as positioning herself just the right way to use her cat-eye glasses to see a reflection of her students while she's writing on the blackboard. She's used this trick hundreds of times and hasn't had a problem until this year, when she starts noticing her students changing shape behind her. Whenever she turns around the students look perfectly normal, so, at first she thinks she's imagining it. However, as the year progresses, she notices that more and more of her students are shapeshifting. SPOILER: This eventually leads to her taking each of her students, one by one, down to the copy room (I think) and shoots them.

I assume this would be yaf, but I can't be certain. Thank you in advance!

[Emlen]

I can't remember the title or collection, but this was definitely a Stephen King short story.

[Michele]

It's "Suffer the Little Children" and it's in Nightmares And Dreamscapes

[Becca]

Thank you!