9 x 13 pan, put foil in pan and oil well.

5 c. rhubarb, cut up in 1/2 inch pieces
1 (3 oz.) strawberry Jello
1 c. sugar and 1/2 c. brown sugar
1 pkg. yellow lemon cake mix
2 tbsp. tapioca or other thickening

Mix rhubarb, Jello, sugar and thickening. Set aside. Mix cake batter as directed. Pour cake mixture over rhubarb mixture in 9 x 13 pan. Bake 1 hour at 350 degrees. Cool and serve with Cool Whip or ice cream.