Before I begin, I must give full credit to Catlin Tucker, who gave me the idea a few years ago to ask students to fill out a form arguing their source's credibility.
Helping students understand if sources are credible is not an easy task, but it's an important one as we teach them to do research. Despite being "digital natives," looking for source credibility isn't something that comes naturally to them. I think a big part of it is they want the first source they find that gives the support they need to be the one they use. Sadly, there's a lot of garbage on the internet, so that's not usually the case.
We start by examining the CARS Checklist for credibility when finding sources. (I'd like to ask McGraw-Hill to fix the typos on this article so that my students stop telling me it's not a credible source as they read that typos often make something not a credible source.) As they read this year, I asked them to fill out a simple table to note the things they should look for in each section of CARS.
Now that they're writing a research paper, they're filling out this source credibility form, which asks them to shows evidence of the credibility, accuracy, reasonableness, and support. Honestly, they hate it. They think it's a waste of time, and I just had to send them an email reminding them to fill it out before they use the source in their essay. However, I believe the little bit of extra time is so important in teaching them to find a worthy source. (Make a copy of the spreadsheet of responses in order to copy the form for yourself.)
Once they fill out the form, I use my newest tool obsession: Autocrat. I know I'm a little late to the party, but I love how Autocrat can give students (and me) their form responses in a Google Doc or PDF format. It uses a template like this to match tags with form submissions. You can view a tutorial by Jay Atwood here.
Once they get their Doc of responses, there's only one blank left: the MLA works cited entry. Since they already have the source URL, my students use their Easy Bib Add-On to create this entry right within their document. And when that doesn't work, they hop onto Calvin College's KnightCite & input the information themselves. I love how easy this is and only wish they understood how much easier this is than consulting the manual and doing it yourself.