This was a tech support question earlier today. It’s neat the way such a simple block creates such a fun 3D design. The block is a simple Attic Window drawn at the halfway point instead of in thirds. To make the quilt diagonally pieceable in rows (sewing the triangles together into diagonal rows), add a diagonal line through the small square too. That’s the way the block is drawn in the project. If you would rather delete the extra line from the block, you’ll be piecing together hexagons when you go to sew the quilt together.