Google Earth is a free virtual environment depicting the earth. It is a
great tool to use for lessons in geography, biology, sociology, etc.
The use of layers in Google Earth allow users to add photos and image
overlays to the learning platform, transforming the tool into
an integrated learning system useful for exploring interdisplinary
content. Fundamental to using Google Earth is developing an
understanding of layers. Follow the link below to the Using Layers
Guide to learn more.