IXL--Math at its most mesmerizing
iCivics (learn about U.S. Government
The National Science Teachers Association
The Robert F. Sibert Informational Book Medal
Our Little Earth-an International Newspaper for Kids
Whyfiles--The Science Behind the News (site closed 2016, archive only)
National Geographic Kids Creature Feature
Discovery Education (including homework help section)
Youngzine (News + More for the Young)
Q-Files The Great Illustrated Encyclopedia
This site lets you find a book based on lexile reading levels, though you do not need to know your child's level. You may also search by grade level and topic. Lots of great suggestions!
Find leveled books and create leveled reading lists.
Book Seller with lists of F&P leveled books.