"Transformativeness" issue in fair use law

I emailed Dennis asking for further clarification of the Fair Use law, particularly the part about "transformativeness", and he suggested that I read the two articles below and then blog about them:

The first is http://en.wikipedia.org/wiki/Transformativeness. This is a wikipedia article. I'm not sure how I feel about trusting wikipedia for this, since it's a potentially emotionally and financially charged issue, but the article does cite several case law examples, and it provides lots of references at the end. I'm not sure that this article was all that helpful for my question about my fifth-graders, though. We're writing a big story on our class wiki, collaboratively, and some students are finding photos online to include. I tried to steer kids towards collections that I knew were Creative Commons licensed, but a few kids went out and got pictures on the open Internet, and while they don't seem to have a CC license they DO fit really well with our story the way the kids have used them. I'm not sure that they're being used "transformatively", though. One way the kids used them is for illustrating historical events (such as the long gas lines during the 1973-'74 oil embargo, or scenes related to the Watergate scandal) that otherwise might be difficult for our audience (kids at our school in grades K-5) to picture. This is very USEFUL for our educational purposes in writing this story, butI can't tell from this article whether it would count as "transformative". (One of my students has also used a picture that I don't know the source for as more of just an illustration, not really of something that's hard to understand.) The wikipedia article cites parodies and the use of picture thumbnails in search engines as examples of transformative uses. Those are such different uses than what we're doing in the case of this story, that I can't really tell anything from this article about whether our use of the pictures would count as transformative or not. (The problem with this article is that it does not give any counter-examples, of cases where the courts ruled that particular uses of online images did NOT count as transformative.)

OK, the next link that Dennis sent is to a whole discussion thread on a wiki:
http://copyrightconfusion.wikispaces.com/search/view/transformative

The first few lines of the first post sound like they would be covered by the article that we already read for class a session or two ago: Someone wants to use copyrighted pictures to set up a protected search environment in order to teach his students media literacy skills. Except for the fact that he wants to sell his product (which both that original article and the one I just read, above, say that contrary to popular belief is not automatically an issue, but might be), this sounds like exactly the sort of use that WOULD be considered OK.

I followed the link to continue reading that post, and a response to it gave a link to a tool to use to try to reason through fair use questions:
http://copyrightconfusion.wikispaces.com/Reasoning

It looks like it might be useful, but I am WAY too tired, and way too much in need of spending time with my husband and my young daughter (who's been running a fever of 101 - 103 degrees F all weekend), and way too much in need of focusing on my regular teaching curriculum and my report cards (24 of them, due in two weeks, and each will take at LEAST an hour, probably longer, to do) -- to spend any more time on this right now.

Dennis, as the instructor for this course, please, if you feel that you have a good sense of the answer to my question, given the additional details that I have now given you in this post about what my students are actually doing with the pictures and why, would you please answer my question directly? I appreciate the additional resources and will read them in more detail after my report cards are done (which means after Jan. 29), but in the meantime, if you would use your greater experience and knowledge base in this field to try to answer my question yourself, I would really appreciate it. Thanks.