Books:

The Gifted Kids' Survival Guide by Judy Galbraith

101 Success Secrets for Gifted Kids by Christine Fonseca

 

A list of kid-friendly sites for curious learners:

Hoagies' Gifted Page for Kids and Teens

Wonderopolis

Kids.gov

Discovery Kids

The Artist's Toolkit

Free Rice

Multiple Intelligences

Brainy Kids

Neuroscience for Kids

Ask a Biologist

Brain Boosters

OLogy for Kids