NASA's website for students, specifically 5th thru 8th grade level in your family's case...

Sky and Telescope Magazine's website, including but not limited to the "Observing" links on the left-hand side of the Home page....

Space.com's website, which includes alot of "Gee Whiz!" multimedia content, as well as a HUGE searchable data base relating to anything astronomy-related...

AStronomy Magazine's website...

Everything you need to know about the moon-sun-earth system, including lunar phases, eclipses, moon features, etc. at...

Finally, here is a link to a very good copy of the H-R diagram

(Hertzsprung-Russell) which astronomers use to catalog and plot stars by brightness (y-axis) and color/temperature (x-axis)...