In Class: Concerns of Unit 2

So as I began thinking about the possible topics I could choose for our Unit 2 Project I started to feel really overwhelmed because especially in English classes I am used to being pigeon holed to one specific topic. I'm not exactly sure what constitutes "too broad of a topic" and that's the thing I need most help with. I was wrestling with the idea of doing the legalization of medical marijuana but I have a feeling that it is too broad. I also am kind of confused about the whole primary source thing because when I started thinking of my topic I realized that I didn't really know if there were any primary sources that I could use to analyze my topic. I would like to get a further understanding maybe with some examples of good primary sources for a topic. I just need help deciding whether this would be a worthy topic.