Exploring Nature is a nice educational resource. There is a paid version (very reasonable $25-$100 a year) but I was able to access lots of their free resources that were terrific. There are 3 free levels to choose from. I found many beautiful, eye-catching graphics, maps, diagrams etc. throughout the free areas. The national standards are available for each theme and I also accessed many nice PDF’s ready to print. They also have a treasure trove of free activities that will lend themselves very nicely to your lesson plans. I was happy to see all of the free nature movies that can be accessed. This is one of the nicest nature sites I have seen.
I am adding this to my Nature/Wildlife LiveBinder.
Below is a screenshot of Discoveries and Inventions. Very interesting and informative.