My students are required to make contributions to this site, which can be in form of new posts, or comments on other posts. Here are some guidelines on how these two types of contributions should differ.
- Comments should be shorter.
My advice is 100-200 words for a comment, 200-400 words for a post.
- Posts should gather information from more sources.
A post should never be just a report on a single article that is available elsewhere. Instead, a post should briefly summarize that article, provide a link, and then go beyond the original article and provide another related source, or background material, or your own personal experience.
- Comments should be focused and brief.
It is perfectly appropriate for a comment to be a reaction to the original post, with a link to one new source of background or other related information. In fact, if a comment has more than one source, it is possible that it would be better to break it up into two comments. (That would depend on whether the two would really stand on their own, or just be echoes of each other.)
No matter which type of contribution you make, be sure to make it interesting and original, and follow the basic guidelines for attribution.