Blogs?!?

While I was doing my homework for this class last night I was struggling. We were suppose to come up with a lesson plan to teach our students about blogs, however I don't read any blogs and I guess I still don't really get their purpose either. Well let me clarify- I don't see why a journalists would have one. I get the mom blogs where they share tips or complain about things and I've seen food and fashion blogs, but I'm struggling with the news blogs? From what I've gathered news blogs are a place for a journalist's opinion on current events. Please chime in at any time if I'm wrong or if you can explain this to me, but if a journalist is blogging about their opinion, then it isn't a source for news but instead a source for their opinion, right? As a reporter they wouldn't post news stories there because those would go in whatever publication they work for. I guess a freelance journalists could put work there as a sample or hoping their work gets picked up by a publication, but still the purpose of the blog is not news, it's self promotion. There is nothing wrong with self promotion, but it changes the intent of the blog. This blog I have here is for an assignment yes, but also to share resources with colleagues and students. I guess I could publish the articles I've written for class here, but does that make it a blog? The mere presence of a few news article? In the end I'm just not sure there is such a things as a "news blog".