Mix together crumb topping. Press half of the mixture into a greased 9 x 13-inch baking pan.
Cover with chopped rhubarb.
Combine remaining ingredients in a saucepan and cook over medium-high heat until the mixture is clear and may begin to thicken. Stir often to avoid burning. Pour over rhubarb.
Top with remaining crumble. Bake uncovered at 350°F for 50 to 60 minutes.
Notes
Rhubarb can be substituted for half rhubarb and half strawberry mixture if preferred.