Blog comments are a good way to build good backlinks, but be sure they are not already spammed a lot! But keep in mind those backlinks are not so powerful nowadays as they were a few years ago, as a lot of people already tried getting such links.
Most of the edu sites block comments on their blogs. The other way of getting link is paying someone who has connection with such sites.
Try use this tool to find .Edu or .Gov backlinks for free to post your blog comment. http://www.freedirectorywebsites.com/seo-tools/backlinks-builder-tool.php