Reuseable sections/items

I'm starting a project with an education professor who's interested in building an Omeka site focused around topics for high-school social studies.

The basic layout would have a series of questions at the top level ("Is violence justified in the quest for peace?") with sections for topics relating to the question ("Dropping the A-bomb", "Nat Turner's rebellion", etc) and then items relating to those topics available off the subsection.

This would seem to be an obvious exhibit->section->page scenario, but we'd like to reuse sections. For example, the Nat Turner section could also be used in a "Could the Civil War have been averted?" exhibit, and recreating it seems to be a waste of effort.

In a similar vein, I could try and use collections to do this, but it would be really useful if items could belong to more than one collection. Ars Synthetica does this nicely with nodes rather than items, including a very nice "Collections containing this item" feature, but I can find no documentation for nodes anywhere.

Can anyone give me a hint how we should go about this? Apologies in advance if this is obvious, but I've been going around and around and haven't figured this out. Thanks

Items, as you've noticed, only can belong to one Collection, and this behavior is by design. Similarly, there's currently no way to re-use exhibit sections or pages.

However, another potential way you can group your items would be by using tags. You'd likely have to do some groundwork in your public theme to get this working, but items can have multiple tags and Omeka can can retrieve, say, all the items with a given tag.