On a recent Friday afternoon, Sandra Hill leads a painting class at an arts center nestled amid rolling Virginia hills, about an hour and a half drive northwest of Washington, D.C.
Each of the 10 adult students has a canvas balanced on an easel in front of them. They're dabbing paintbrushes loaded with dark green paint along the edge of a lake, the beginnings of a glowing sunset in the background.
"And think tree! Don't just go tap, tap, tap any old place. Remember, trees have depth to them!" she reminds the class.