New Websites For Kids:
Ask a Biologist will connect you to experts who can answer all of your scientific questions about animals and biology.
Bug Guide is an online community all about insects, spiders, and other creepy crawlies.
Code Monster is a fun way to learn computer coding.
CSI: Web Adventures lets you solve crimes & exercise your detective skills based on the fictional show CSI; this site was sponsored by the National Science Foundation.
I Was Wondering is a project of the National Academy of Sciences and showcases the accomplishments of women in science.
Middle Shelf has free online magazines published for kids & teens.
San Diego Zoo Kids is a fun, interactive site with games, videos & photos of amazing animals.
Smithsonian Tween Tribune is a free site offered by the Smithsonian for use by K-12 grade teachers & students. (added 6/15/15)

Kid-tested, Librarian-approved: check out this collection of great websites for kids recommended by librarians across America.