Caltech Outreach
This site gives a large number of categorised Educational Astronomy links and is an outreach activity by the Communications and Education (ICE) team of the "Infrared Processing & Analysis Center" (IPAC).  Go here. (Look in the Outreach menu or scroll down on that page).

SKA for educators
Outreach and Education resources by the "Square Kilometre Array" (SKA) team.  Go here.

ASP Education and Outreach
The Astronomical Society of the Pacific (ASP) has a comprehensive collection of resources and information for teachers and students as regards teaching and learning Astronomy. Go here.

ClassAction modules
by the University of Nebraska-Lincoln, consist of questions and resources designed to encourage student engagement in the classroom. More details can be found on the overview: how to use and the pedagogy behind, the pages. The PowerPoint page gives some guidance on importing ClassAction resources into PowerPoint. The modules listed roughly follow the outline of most introductory astronomy textbooks. ClassAction is still being actively developed, so some topics are covered more thoroughly than others. Go here.

The Nebraska Astronomy Applet Project
also by the University of Nebraska-Lincoln University, provides online laboratories targeting the undergraduate astronomy audience. Each lab consists of background materials and one or more simulators that students use as they work through a student guide. Pre-tests and post-tests can be used to gauge student learning. These are awesome modules, several of which we use ourselves regularly in our courses. Go here. (You can download their Native Apps).

Educational Resources for Astronomy 101
This is a collection of digital resources by astronomycenter.org, for college-level introductory astronomy faculty and students. Astronomy Center is brought to you by the American Association of Physics Teachers, and the National Science Digital Library. Go here.

CosmoLearning
By Merlot is a free K-20 educational, web media site for students and teachers. This resource links to the Astronomy section. Go here.

Royal Astronomical Society of Canada
The goal of the Education Committee of the Royal Astronomical Society of Canada is to help parents, teachers, students and the general public learn more about astronomy. In particular check out the category “Classroom Help” and "Extra Resources". Go here.

ESA Education Office
The European Space Agency (ESA) has from its inception been focussed on supporting education in the area of space. Several in-resident activities are only available to ESA member states, but there is a wealth of resources, information and ideas on the ESA Education website. In the "Teacher's Corner" you will find classroom resources "Teach with Space" for primary and secondary level with guides and worksheet that can be downloaded.

ABC Science
ABC Science gives many links to the latest science news. The "Space" section is of interest for Astronomy and Space Science. Go here.

Science in School
is the European journal for science teachers. Its website has the tabs "Inspire", "Understand", "Teach" and an Archive of previous issues. Check out the "Astronomy / space" component in some of these tabs, listing topical articles in recent issues. Go here.