1. Wash and drain blueberries. 2. In a medium saucepan, mix sugar, 1 cup of the blueberries, cornstarch (use heaping tablespoons with frozen berries), salt, water, cinnamon and lemon juice. Cook and stir over medium heat until thick. Remove from heat. Immediately add margarine and remaining berries. Stir until sauce is mixed with all of the berries and margarine is melted. Pour mixture into prepared pie shell. 3. Keep refrigerated until serving time. Serve with whipped topping or ice cream.