I came across a strategy which I will hopefully practice when the next unit of inquiry starts. I forget whose idea this is...but it's a great one. At the beginning of each unit, we collect resources for the children. My colleague and I go down to the library and get as many books as possible. We delve into the messy unit boxes, items which have been sitting there long forgotten. (We need to create virtual unit boxes in order to see what's in them from the confines of our desks!)
So the idea is to let the students look at the central idea and inquiry lines and then go through the resources themselves. They should be able to identify which resource will help them with their research work, which ones will address an inquiry line, etc.