(TOP) Art instructor  Millie Greene (left) teaches a plein-air  oil painting class to Cathryn Sacks (center) and Rhanda Nelson (right) at Santa Monica Beach on Wednesday, July 08, 2009. En plein air is a French expression which means "in the open air", and is particularly used to describe the act of painting in the outside environment rather than indoors (such as in a studio). (ABOVE) Millie Greene's oil painting on Wednesday, July 08, 2009.