"Field Trip Earth is the global resource for teachers, students, and proponents of wildlife conservation.
Click on one of the field trip icons to begin your journey, or view a list of "
"Providing the scientific basis for effective conservation, NatureServe and its network of natural heritage programs are the trusted source for information about rare and endangered species and threatened ecosystems"
The University of Pennsylvania Health System provides nearly 200 video animations and explanations of injuries, diseases, and body systems. The animations, like this one of a balloon angioplasty, are concise which makes them good for general reference purposes.