Assemble the Block
1. Sew together one red print triangle and one white print triangle to make a pair (Diagram 1). Press the seam allowance open. Repeat to make a total of four pairs.
2. Join a blue print triangle to each Step 1 pair to make a windmill unit (Diagram 2). Repeat to make a total of four windmill units.
3. Sew together the windmill units in pairs (Block Assembly Diagram). Press the seam allowances in opposite directions. Then join the pairs to make a block. Press the seam allowance in one direction.