In a large bowl, combine the flour, oats, brown sugar and salt. Cut in shortening until crumbly. Press half the mixture into a greased 9-in. square baking dish. Bake at 350 degrees F for 10 minutes or until brown around the edges.
Combine blueberries and sugar; sprinkle over crust. Top with remaining oat mixture; press down gently. Bake 35-40 minutes longer or until golden brown. Serve warm.