"So you're gonna be a librarian? You realize that job will be obsolete soon right?"
--Only if the world actually ends in 2012.
Yes, I love Google. It's a very handy source for fast searches. I also love Wikipedia. It's the best way for me to get synopses of horror movie plots when I don't actually want to sit through the blood, gore, and stupid half-clad girls running upstairs instead of out the already open door.
But just because they're good for fast searches and brief introductions doesn't make them reliable sources, especially for younger students who don't have a firm grasp on the research process. It's statistically proven that when children search, they don't look past the first few results they get. They also like to search in long phrases and when they don't get any good results, they either change the order of their search terms or change the spelling. Really, children can't rely on Google for finding all of their research information.
Let's try something. Go Google "Barack Obama biography." After the ad at the top of the page, you'll see that the second result given is his IMDB page. I would LOVE if a student turned in a paper that cited information about the President from a movie database (my sarcasm hand is raised). The actual White House biography isn't listed until the bottom of the first page. There once was a link to "barackobamaismyhomeboy.com" on the first page. Thankfully, this one is no longer available.
Next, let's try a Google image search for "spears" as if you need it for a medieval weapon project. Every single result is of Ms. Britney. Even if you do a singular "spear" search, you get a good amount of Brit Brit.
Then there's Wikipedia. I think it's a great source for getting a good overview of topics, but it shouldn't be a student's sole source of information. Especially because anyone can edit the pages. Remember what happened when Stephen Colbert told users to edit the elephant page to say that the elephant population had tripled? Pages can be hacked all the time. Of course there are monitors on the site, but you can't catch everything.
So where can you find more reliable information? Maybe it's a long shot, but I'm thinking libraries and the awesome librarians who work there can help you out.