Some of my past non-fiction writing has been in the childrens/educational vein. I'm a bit out of touch at the moment but I would suspect there are many review sites that you could send copies of your books for review. Also be sure they are categoriezed appropriately at the outlets you are selling through assuming you are (Amazon? Smashwords? etc.)
Promote your books on any reading/literature sites (such as this one) appropriately (see the author/blog self-promotion subforums).