I am starting to publish in my Bulgarian blog a series of texts fitted to serve as a biology textbook for school (grade 5-6), as I want to see it. Details here.
My Bulgarian blog is generally a short version of this blog. However, at present I don't intend to translate the primary school-level teaching materials to English. It isn't clear at this stage whether I'll finish the work successfully even in Bulgarian. So, if you are a Bulgarian reader interested in the "textbook", check my Bulgarian blog from time to time.