- In a large bowl, combine the strawberries, raspberries and blueberries. Combine sugar and tapioca; sprinkle over berries and toss gently. Pour into a greased 11×7-in. baking dish; let stand for 15 minutes.
- Meanwhile, in a small bowl, combine the flour, oats, brown sugar and cinnamon. Stir in butter; sprinkle over berry mixture.
- Bake at 350° until filling is bubbly and topping is golden brown, 45-50 minutes. Serve warm and, if desired, with vanilla ice cream or sweetened whipped cream.