Man, there is so many factors, that it is almost impossible to answer without seeing your site. It can be ads relevance, site design and the look of ad units etc etc... Your ctr could be acceptable. Low but quite normal for some kind of sites.
do educational sites tend to get much? how about sites about video games? (discusion boards on video games, cheats etc...)
You know alai - you should do some tests with another ads order on your site. It would be really better to remove this one which is on the right side (almost bottom of the site) and put a high skyscraper on the left. This would be first of my changes. You can add some horizontal links units somewhere - it should help too.