Preheat oven to 400°F (200°C). Roll out half the pastry and line a 9-inch pie pan; trim crust to the rim of the pan. Loosely cover with plastic wrap and refrigerate.

Combine sugar, tapioca, and cinnamon. Toss sugar mixture with blueberries and sprinkle with lemon juice. Let stand 15 minutes. Roll out the top crust into a 10-inch circle. Cut into half-inch strips. Pour blueberry mixture into chilled pie shell and dot with butter. Add the pastry strips one at a time, weaving a lattice. Flute edges.

Place pie on a baking sheet to catch drips. Bake for 40 to 50 minutes until filling bubbles and crust is light brown. Cool completely before serving.