Wildlife and Nature Sites
It's sister site Wikimedia Commons is a good source for photos and other multimedia.
Other good sources are Free Public Domain Photo Database
Freephoto.com  Classroom Clipart and there is some nice clipart of British Wildlife at WildBritart.com
click here to visit Planet ARKive.
click here to visit ARKive Education.
A good source of information is Wikipedia the free encylopedia that anyone can edit.