c("Mix  flour, rolled oats, brown sugar, margarine and cinnamon until crumbly:   Press half of this mixture into a 9\" greased pan.", "Cover with  chopped rhubarb.", "Combine sugar, cornstarch,   and water.", "Cook until thick and clear in a small saucepan.", "Remove from heat and add vanilla.", "Pour over rhubarb. Top with remaining crumbs.", "Bake at 350°F for 1 hour.")