Nine-patch quilt blocks

A nine-patch block is three squares across and three down. Fill every square with plain fabric and it is the Nine Patch; put quarter-square triangles in the sides and it is an Ohio Star; half-square triangles in the corners and it is a Churn Dash or a Shoo Fly.

The 3 × 3 grid cuts cleanly at sizes that divide by 3, so 6″, 9″ and 12″ blocks all measure on the ruler. Sew it in three rows, then join the rows: the order is the same whatever goes in the squares.