I have long believed Google Earth is an excellent platform for education. Recently, I discovered a new web site called RealWorldMath.org, which uses Google Earth as a platform for teaching basic math concepts. The site is run by Thomas Petra, and includes a number of lesson plans with helpful GE KML files to help get the process started.
As an example, I tried out the Volume of Solids lesson, which uses real world objects to add some interesting geographic perspectives to basic shapes for learning how to measure volumes. The lesson KML file
shows a variety of basic geometric shapes by leveraging the 3D Buildings layer and picking locations with buildings (or other objects) for each shape. For example, the Reunion Tower in Dallas for a sphere.

I like this concept of combining geography learning with math, and real-world applications. There are several other lessons on the site with equally interesting applications and I think will captivate the minds of students.
Related:
Educational Uses for Google Earth
Real World Math Using Google Earth
September 9, 2009
ooh, have you seen this yet?
http://google-latlong.blogspot.com/2009/09/google-earth-51-think-fast.html
According to the Lat-Long Blog, Google has released Google Earth 5.1.