Oil is a complex medium, therefore the process of learning the medium alone is lengthy. For children and adults, the focus should be on the development of drawing and painting skill rather than dealing with the medium. I reserve it for my commission work, and prefer not to teach it. Oil paint is a medium to be embraced later in one’s artistic growth. Until recent years, oil painting required the use of mineral spirits as solvents. Today, water-soluble oils are available and gaining wide acceptance because of their non-toxicity and easy cleanup. I have switched to these for my commissions and recommend them to other artists.