Rhubarb Raspberry Crunch

My dad found a rhubarb patch in the trees behind our house when he was here last weekend, and mom brought some frozen raspberries from their patch with them. I went to allrecipes, where you can enter ingredients to find recipes that use those ingredients. I entered rhubarb and raspberries, and this is what I decided to make.

• 1 cup white sugar
• 1 tablespoon instant tapioca (I didn't have any tapioca, so I added an extra tablespoon of cornstarch)
  
• 1 tablespoon cornstarch
• 1/8 teaspoon salt
• 4 cups rhubarb, cut into 1/2 inch pieces
• 1 cup raspberries
• 1/2 cup brown sugar (I increased the brown sugar, oatmeal and flour to about 2/3 cup each)
  
• 1/2 cup all-purpose flour
• 1/2 cup quick cooking oats
• 1/2 cup butter, chilled

Preheat oven to 350 degrees F (175 degrees C). Grease a 9x13 inch baking pan (I used an 11 x 7 pan).
In a large bowl, combine sugar, tapioca, cornstarch and salt. Place rhubarb and raspberries into bowl making sure to completely coat them with dry ingredients. Pour into baking pan.
In a medium bowl, mix together brown sugar, flour and oats. Cut in butter until mixture resembles pea-sized crumbs. Spread on top of fruit mixture.
Bake in preheated oven for 45 minutes, or until rhubarb is tender.
Tastes good plain; tastes even better with whipped cream or ice cream.