In this video segment [3:10] from Cyberchase, the CyberSquad must find the exact center of a circle in order to save Motherboard.

Circle Geometry math for kids contains information for students to learn about terms radius, diameter, circumference, chord, and pi.

In this video segment from Cyberchase, the CyberSquad must reclaim the Totally Rad Ring by measuring its radius to create a perfect duplicate.

The Math Forum offers an archive of question and answer sessions on circles and how they relate to geometry.

Can there be a connection between map making and math? Explore the mathematics of cartography in this resource that integrates web-based instruction, mathematical problem solving, geometry, history, and art. Interesting information and...

This site from the Astronomy Department of Cornell University provides brief introduction to both solar and lunar eclipses. Links are provided for pictures and charts of the eclipses, and this is a good site to check out on the subject.

Official NASA information page about the planet Mercury.

Excellent resource for "paper-plate" activities that help simplify various astronomy topics. Learn how to build a "Moon Finder" and "Planet Pointer," and create a paper-plate model that explains the Transit of Venus.