Starchitect
Starchitect is a free astronomy education game about stellar and planetary evolution. Here you can create different types of stars, then add planets, and even try for life. All of this happens at a million years a minute (for reference, that would make our solar system about three days old).
STEM Clearinghouse
In the STEM Resource Clearinghouse, librarians and library staff can find high quality, vetted STEM activities that are appropriate for library use.