How does the ordering of the articles on the main site front page go? I read that it is organized in terms of ratings, high to low I would presume. However that does not seem to consistently be the order, on my page at the moment I see a rating of 7 above a rating of like 19. Is this a temporary thing that occurs for the newest articles? They shoot to the top of the page for 24 hours or something?
And for that matter, what does the rating signify or reflect? Does a user rating an article 3 stars out of 5 directly grant the overall rating 3 points or something?

Rating 3/5 = 60/100 for the general rating of the article. The general rating of an article is like a weighted grade made out of user's grades and writer's grade or something like that. That was the answer I got when I asked.

Also it wouldn't make sense for articles to be sorted by grade instead by their time of posting.

For now, the articles are sorted by day. So an article written on the 24th will always be ahead of an article on the 23rd, regardless of score. This restriction will go away in time, but is necessary now due to limitations in finding fresh content otherwise.

As for the score itself, as be.redy said, it's a combination of multiple factors. A score is generated based on grades users give it, number of views, number of grades, number of comments, etc. The single highest factor is the grades users give to the article. This algorithm will be tweaked over time.

Thank you for clearing that up, was just curious.