Hi Rhian
I can’t say that I have done this but do know how I would do it if I had the chance. I am sure someone more well-read than me will point you in the direction of research but for what it is worth here is how I would go about it.
Using one of the workbooks on this website – Alfred the Great is a good one to start with that you can change to whatever topic you want. Decide on your topic with the teacher and think of a great overarching question (this can be the tricky bit and people on here will help!). Make sure as the librarian you have enough resources that can be used to answer this question. If you can add website links to your library catalogue add any you find or your teacher recommends as your first research tool. Then check any academic online resources you have ie Britannica or Q-Files for instance. Once you have a question and are happy with your resources offer lessons on how to access them and the teachers need to say that only these resources can be used for this homework task. A quick lesson on how to reference will ensure you can see where the information has come from and the evidence of how much better this homework is will speak for itself.
I have tried to make this brief so if it does not make sense then just ask…