A tad similar to this question here but also quite different, so here's the current debacle:
In one of my classes I taught, the final project entails students getting in groups and having to run a mini experiment of their own. One of the groups had a very cool idea that I thought was great and unique but didn't give much thought to. Fast forward about half a year or so to now. I revisited their idea and realized that their idea could, in fact, be a Study 1 that's part of an overall larger series of projects I'm hoping to conduct. Of course, because their study was a class project (meaning that it has no IRB, sample size is extremely small and therefore statistically underpowered, no supervision from faculty or grad students for quality check, etc.), I can't simply slap their results on my paper and give them coauthorships like you might do with other collaborators.
That being said, I'll have to run a replication study of their idea to meet publication standards and rigor. Normally, I would see if the students would want to be research assistants to help me replicate their study and give them coauthorships on any posters, oral presentations, or papers that come out of this. However, I don't think I'll be able to get the study started for a while and all these students are currently 4th years (meaning they will graduate in approximately 6 months).
With that in mind, is it ethical to replicate the study with my own batch of research assistants in the future and give credit to the class students in only the acknowledgement sessions for giving me the idea for one of the studies in the paper?
Or would one have to give authorship to the students? I personally follow a code of publication ethics where authorship is mainly reserved for those who played a role in the actual writing of the paper or collection of primary data but of course am open to hearing out other opinions and changing my code. (Note: my field is Psychology)
Small edit: I see this case as being different from citing published papers or preprints given that the work is still novel and not published. But the students' project is actually on Youtube so it can be regarded as public. Perhaps I'm intuitively sensing that it is different given that they were my direct students.
Final update (5/11/22): I've since changed my approach and now agree with others that intellectual contributions warrant giving credit to in the form of coauthorship. Unfortunately, the specific project that spurred this question never came to fruition due to the COVID pandemic as it required in-person activities.