Preheat oven to 375 degrees.
In a large bowl, combine rhubarb, sugar, flour, and cinnamon.
Place in a greased 9-inch by 2-inch deep in a baking dish.
Bake uncovered for 15 minutes.
In a bowl, combine flour, sugar, baking powder and salt.
Add butter and milk stirring just to form a dough.
Drop tablespoons of dough on top of rhubarb.
Bake at 400 F for 20 to 25 minutes. Serve warm with vanilla ice cream if desired.