I had to think a little on this one.
The block could definitely be pieced traditionally but I have found that, because these blocks are so small, foundation piecing is the most accurate way to go on most of them.
Trace or print the block diagram onto foundation paper, number, and cut out as in the photo. I use freezer paper for my foundation piecing. If you don't, you will have to trace the center sections onto freezer paper for the applique.
Foundation piece the numbered sections and trim the seam allowances to 1/4".
Cut a 4" square out of your main fabric. Iron the freezer paper cutout of the block's center section onto the right side of this square.
Iron the small half-melon sections onto the right side of your background fabric and cut out, leaving a scant 1/4" seam allowance along the curved edge and at least 1/2" on the straight side.
We are going to use the edge of the center freezer paper as a guide for our applique.
Place a melon freezer paper side up on top of the background fabric square. Carefully line up the curved edge of the melon freezer paper with the curved edge of the center section freezer paper (as they were before you cut them out) and baste through all layers. A light table is very handy for doing this because it allows you to see through the fabric. You could also hold the fabric up against a bright window.
Repeat for the opposite melon.
Applique the melons onto the main fabric square along the curved edges, turning under the fabric as you go and using the center freezer paper shape as a guide for your curve.
Repeat on the other side, remove the freezer paper from the melons, and press.
Repeat for the other two melons.
Trim the block to 2 3/4", making sure to center everything. At this point you can trim away some of the extra fabric bulk, but I didn't because I was worried about the square losing its shape.
Sew the foundation pieced sections to the sides of the center square, lining up the seams carefully.
(I used the same technique on block B-7.)