If you teach biology, you need to look at the information pulled together at The Encyclopedia of Life.
There are about 1.8 million known species of living things on Earth. It is the ambitious goal of this site to provide in-depth information about each and every one of these species. There are plans to create a “site” for each species. The individual species sites are all under the main site: http://www.eol.org/index so each is visually and structurally consistent. The information that populates the species’ sites comes from many authoritative sources, and there are institutional contributors including the Smithsonian Institution, Harvard University, Chicago’s Field Museum, and many more. Most of the information has Creative Commons licensing so it is easy to use in your educational materials, the ones you create yourself, the ones that enrich the classes you teach, what you do that goes beyond the textbook your school or district gave you.
This image of Cardinalis cardinalis, the common cardinal in the U.S. is provided without any restrictions on its use (and that’s why I included it here).
Beyond basic descriptions and images of the species, there is authoritative content about classification, behavior, reproduction, life history, morphology, maps of distribution, and much more.
Of course, for those of you who have researched a species, you can become a contributor, even if it is simply a good photograph, for example.
I do have one quibble about the otherwise excellent resource. When I entered “Cardinalis cardinalis” to look up the example used here, I was presented with an alphabetical list of 198 species that fit the words I entered somehow. It was necessary to page down (did you know you can do that with the spacebar?) until I got to the common Redbird link. It didn’t take me long to decide that wasn’t a problem, but you might want to warn your students about it. Actually, entering the common name “cardinal” automatically lead to a different list based on common names instead of scientific names used in the first search. The common “cardinal bird” was still a way down the alphabetical list, but that’s the same quibble.