Google Earth is a dynamic interactive digital globe that students and teachers can use to explore how humans interacte with the planet Earth. Even though Google Earth is a digital globe, it can be used to engage students in not only for geography, but also most other classes including history, science, math, and English. The web sites linked to below provide examples and strategies for using Google Earth for student learning.
WWII Historical Imagery in Google Earth
Google Earth for Educators - 50 Exciting Ideas for the Classroom
Teaching (and Learning) with Google Earth