Once third grade rolls around, a student's homework suddenly becomes more involved ("Mom, when did the saber-toothed tiger become extinct?"). If you find yourself without the answers and you're (understandably) squeamish about turning your 8-year-old loose on Google, check out one of these online subscription-based learning resources for kids.

WorldBook Kids at worldbook.com
With access to the Student Discovery Encyclopedia and the grown-up World Book, the site's loaded with reference materials, from antique world maps to a clip of the noise a roadrunner makes (no, not "meep, meep!"). And the printable activities are particularly good, says Ronald Fortune, CEO of Education.com, especially such science experiments as a DIY planetarium. ($4 for three-day access, or $50/year)

Cosmeo.com
From the folks at Discovery Channel, Cosmeo is a trove of multimedia info, including 30,000 videos that make everything from the Great Barrier Reef to grammar come alive. Cosmeo's specifically designed to help with schoolwork, with lessons that complement the major textbooks and state-mandated lesson plans -- best, says Fortune, for kids needing a hand with math and science. (Free 30-day trial. $10/month or $100 for a year) 

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