In medium saucepan combine cocoa, milk, margarine, and sugar. Cook over medium heat, stirring constantly. Bring to full boil and allow to boil 1 min. Do not over boil. Stire in vanilla. Pour chocolate mixture over oats in a large bowl and stir. Drop with teaspoon on wax paper. Let cool about 1 hour. For a little variation you can add coconut or nuts when combining the chocolate mixture wih the oats.