In our schoolhouse, we try to do a weekly art lesson as part of their visual arts requirements. These standards are very general and give a lot of leeway for interpretation, so we end up doing a lot of tie-in to other subject areas, especially science. Art is a wonderful way to not just learn a new way of self-expression, but also to truly look at nature with artist eyes and appreciation.
Since we live on an island, we often go down to the flats to gather sea creatures for our salt water tank, but another great resource are the dads, who are out lobstering day after day. They find the most amazing creatures in their traps and all we have to do is give a shout out on the VHF radio that we need some new creatures for our tank and they'll bring in a bucket of goodness or we'll meet them at the town dock to collect what they've gathered.
In art class, we put the creatures into smaller, see through plastic tubs full of fresh sea water. Every table gets a different group of creatures to examine and draw. We work on perspective and shading, as well figuring out just what sorts of colors really do it justice. Their ability to really "see" what's in front of them rather than a preconceived archetype of what a fish or a shell looks like has greatly improved and has transferred to many different areas. We've drawn all of our classroom potted plants, gone outside to do perspective drawings of our playground and of course, ourselves.
Right now we are creating an undersea mural in our downstairs bathroom. The kids choose sea creatures from our area, find examples in our field guides to help them with details and coloring, then sketch an outline which we photocopy onto plastic overhead sheets. They use the projector to enlarge the images and trace the outlines on the walls which they are beginning to paint. I cannot tell you what a wondrous feeling it is to go into that bathroom now. It was a nice lesson that even if you can't always get outside, try to bring the outside in as much as you can. It changes the entire feel of the classroom environment.