From Background: Cut 1 - 4 1/2" strip. From this strip, cut 4 - 4 1/2" Half Square Triangles (HST).
Cut 2 - 2 1/2" strips (or cut 1 strip and then you will need to cut 1 or 2 - 2 1/2" squares from the 4 1/2" strip). From these, cut 10 - 2 1/2" squares.
From Main color: Cut 1 - 4 1/2" strip. From this strip, cut 4 - 4 1/2" HST.
Cut 2 - 2 1/2" strips (or cut 1 strip and then you will need to cut 1 or 2 - 2 1/2" sqaures fromthe 4 1/2" strip). From these, cut 10 - 2 1/2" squares.
Sew Fabric A - 4 1/2" HST to a Fabric B - 4 1/2" HST to make a 4 1/2" HST Square. Make 4.
Sew 2 Fabric a - 2 1/2" squares to 2 Fabric B - 2 1/2" squares to make a 4 Patch unit. Make 5.
Lay out block as shown. Sew rows together. Press seams toward the HST. When sewing rows together, the seams should lock together for easy sewing.