I shared some examples of inquiry/research units on my blog (I haven't updated it in a while).
http://lawlib.weebly.com/blog/category/research These have all been during once-a-week library class separate from the classroom curriculum. I often start with a great picture book and have the students generate questions based on that. Then I have curated resources (back matter from the original book, websites, nonfiction books, videos, Newsela or ReadWorks articles, videos, speaking with experts, etc.) and students use those to find the answers to their questions. Often I will split up the questions and a pair of students will work together to find the answers. There are so many ways to do it, and it isn't necessary for them to do all the steps. I would say I usually take about 4 weeks, but it definitely could be longer or shorter depending on what you are hoping for the kids to get out of it. I would be happy to answer any other questions. Just try it out- you will learn a lot that way, too. Good luck!