If you are submitting a site, make sure that its primary purpose is the actual education of astronomy or astrophysics. Many web sites might seem as if they are meant for education, but would better fit under categories such as Science/Astronomy/Personal_Pages or Science/Astronomy/Images.
There is also a Science/Physics/Education category here at ODP, and they may be more appropriate for some site submissions.
This category is not for software or selling of products.
Science/Astronomy/Education is for educational web sites of interest to educators, parents, students, and professionals emphasizing the teaching or learning of various aspects of astronomy or astrophysics.
The best sites will try to teach or instruct about astronomy or astrophysics, although clear, easy-to-follow explanations of topics are useful as well.
There are also sites here that talk about educational programs of all levels, including - but not limited to, grade school, college programs, and graduate schools.