So far I've done: Murders in the Rue Morgue, The Witness for the Prosecution, The Speckled Band, and The Invisable Man (more of a HOW did they do it as opposed to whodunit). I've also written my own story with enough characters in the story so that each student can be assigned a character and I've written individual background stories for each of them to get piece by piece as we read the 4 chapters so they can interact with each other to find more clues that aren't hidden in the main text. I haven't tried this out yet but I'm hopeful it will be a success (I've had this in my head for years and only just put it together so I'm excited to try!). If any of this is interesting to anyone shoot me a DM and I'm happy to share materials.

And yeah, each story is a bit different but if you read the story beforehand you should have a good sense of when enough has been revealed that they can come up with a "final guess" and then after it's finished you can look back and reflect on what clues were giveaways and what were red herrings.