In a large bowl, toss the berries with the tapioca and lemon juice.
In a separate small bowl, combine the flour, brown sugar, oats, and parmesan. Use two forks or a pastry cutter to cut the butter into the oat mixture until it resembles coarse sand.
Transfer the berry mixture to an 8x8" baking pan and top with the oat mixture.
Bake for 40 minutes, until the top is golden brown and the berries are bubbling.