Patterns in Quiltvillage and American Patchwork & Quilting magazine frequently say: From assorted dark scraps, cut:
To make the triangles, follow these rotary-cutting instructions. Square up the fabric by trimming the raw edge of the fabric.
1. Turn your cutting mat clockwise 180-degrees with the newly cut edge on the left. Find the 3-1/4" mark on the ruler. Line up the 3-1/4" mark with the left straight edge of the fabric. Line up the 1" mark with the bottom fold of fabric. Cut along ruler edge. You now should have one 3-1/4" strip. Cut two more strips.
2. Unfold one strip. Turn it so a narrow end is on the left. Line up the 3-1/4" mark on ruler with the left edge of the fabric, and cut along the ruler's right edge. You now should have a 3-1/4" square. Repeat to cut the specified number of squares.
3. To cut each square diagonally twice in an X, line up the ruler's edge with opposite corners (see Step 6). Cut along the ruler's edge; do not separate the two triangles created. Line up the ruler's edge with the remaining corners and cut.