I am taking a graduate seminar in which we need to plan and write up a research proposal as our final project. The project can be based on any of the topics we covered all semester. During the class where we covered "Topic ABC" I asked whether anyone had ever done a study where they looked at x, y, and z variables (my question was very specific). My professor said that to their knowledge, no one had ever done so, but that it was a very good idea. At that point I started thinking about using that idea for my final project.
The next week after class I was talking to a classmate about what we were going to do our final projects on. She said she was a little worried because the course topic is somewhat out of her area of expertise, but that she " was thinking of doing it on Topic ABC looking at variables like x and y." It sounded a LOT like the idea I'd pitched in class, pretty much the same thing actually, which took me aback and I wasn't sure what to say, so I didn't really say anything. I ended up scrapping my original idea and finding another topic because I didn't want to risk presenting the same project as her (it's a very small class, 6 people, and we would be presenting the projects orally in front of everyone for about 30 minutes each - pretty boring if 2 people pick the same thing). Also I figured since the class topic is closer to my area of expertise than hers it would be pretty easy for me to come up with a different topic anyhow (it was).
We had our presentations this week, and my classmate did indeed present the exact project I'd proposed. She hadn't thought through some of the required logistics though, and the professors were a bit critical of her presentation as a result. My proposal went well and I got positive feedback.
My classmate is a nice person and I don't think she knowingly "stole" my idea, I think she heard it in class and maybe forgot the source. Or maybe she wanted to go with an idea that it sounded like the professors already liked because she was concerned that her own ideas weren't as good, or something, and didn't think about the fact that I might want to use my idea as my proposal. All of this made me wonder, at the point when she told me she was thinking about using that topic, what would have been a polite way to say "Oh, you mean like the idea I was talking about in class?" without it seeming like I was trying to lay claim in a "mine, not yours!" kind of way? And if I had actually been really invested in the topic, is there any way I could have told her that I was already thinking of using the idea without it being awkward? At the time I mostly couldn't come up with any sort of phrasing that didn't sound in my head like "You're coooppying meee!" (thanks social awkwardness).