1 cup flour
3/4 cup rolled oats
1 cup brown sugar
1/2 cup margarine, melted
1 teaspoon cinnamon
4 cups rhubarb, chopped
1/2 cup sugar
2 tablespoons cornstarch
1 cup water
1 teaspoon vanilla

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 degrees for 1 hour.