I think that some teachers get students involved in blogging because it seems like the thing to do, but we forget that it's as important to avoid 'added plates' for the students as it is for ourselves. If we want students to give full, mindful effort to the important learning activities of the inquiry, giving them additional responsibilities that don't necessarily contribute in a real way to their learning may not get you what you want in terms of high quality results. Is an inquiry-based learning activity really the place for a bonus-type assignment? Some students may use this as an opportunity to opt out of the hard work of the inquiry because they can make up the marks with lower level skills like class reporting. As well, no matter which student(s) you assign to the job, you'll still have to monitor closely for appropriate content and usefulness. In Canada, you must ensure that privacy laws are respected and that no personal information about students sits on servers outside the country, so have the students use avatars and pen-names, and choose your blogging service carefully. If it's online, be sure they don't have to register individually in order to contribute. (Edmodo can be a great place for this, or Kidblogs.) Otherwise you can get a Wordpress blog hosted on a school or district server.
If you do decide that you want the students to be writing for you, 'starting with the end in mind' can help clarify the purpose of the blog and how it fits into the inquiry learning process. If you just want a daily news/record, then there's no reason to be disappointed if the links the kids provide are mainly to your own website. That just shows they feel your writing is the most authoritative. After all, simple reporting is just about making the day's content easily accessible to everyone in a central location. I'd work this into the normal marking scheme for the term, get a rota going right at the beginning, and have a rubric that is adapted over time to keep the kids focused on succinct, accurate reporting and good basic writing skills.
If the desired goal is for them to become better at searching for information online, then you'll want to take the time to teach them how to do that effectively, perhaps use a social bookmarking tool (with annotations) like Diigo, and provide a rubric that makes explicit exactly what you mean by 'relevant'. Do you want them to use a variety of sources? How will you get them past Wikipedia? How will you get them to pick work that is actually readable by classmates? How will they determine authenticity? For most people, a Google search stops after 3 pages because they don't know how to sift through the volume of stuff and don't have the patience to keep looking. This can be a great way to teach them an invaluable research skill.
If you want the students to reveal their inquiry thought processes and be reflective, then some examples will be important with class time given to co-developing a rubric so they understand and participate in generating the benchmarks for 'quality'. If you want them to become engaged in a dialogue, then think about what the blog can do that they can't accomplish in class and clarify for them the blog properties that would indicate to you that the writer had understood the spirit of the task.
To sum up ...... I think before we teachers think about assigning blogging to our kids, it can be a good idea to clarify in our own minds what the blog's purpose will be, how the writing will fit into the learning process, and what skills and understandings we want students to develop through this activity. If the blog has no intrinsic value, then it's not unlikely that we'll get perfunctory work from some students -- except perhaps from those who don't need the bonus marks anyway. Good blogging takes quite a bit of time and deserves to be read and responded to, but if it contributes the learning in a real way, the feedback we'll get about the students' development makes the time spent on it (both ours and theirs) extremely valuable. Finally, it's good to keep in mind that blogs tend to be public. Even when privacy is maintained, kids invite others to read over their shoulders and parents ask them to share what they're writing. It can be a good thing to always be aware of the way the public will judge us as teachers from reading our students' blogs.
Here are a couple of interesting links:
1) the blog of a science teacher who is trying out new teaching/learning strategies -- Quantum Progress (http://quantumprogress.wordpress.com/)
2) a series of how-to challenges for teachers who want to try class blogging -- in Edublogs
I can come across a bit preachy sometimes, but I felt your questions deserved some extra time and writing.I hope this was helpful.
-Sue in Surrey
Thank-you for your detailed response, Sue. I appreciate the effort you put in to it.
Perhaps I should have clarified that the inquiry project is my own and not part of inquiry-based learning for the students (although my class does incorporate some I.B.L.). The primary goal is to see if the blog will become a useful resource for the class or generator of discussion. No student will be required to operate or access the blog. If the students want to do so, and it helps them in some way, then I will be as intrigued as if the opposite occurs. This "experiment" operates as completely separate from any on-line research skill-building I teach. I'll check out the links you provided. Again, thank-you for your time.