Check your measurements very carefully. Each block should measure 12 1/2 inches when it is finished. Accuracy from beginning to end will assure that your blocks come out perfectly. Measure carefully, sew carefully, and you will have a perfect block.
For Sarah's Choice you will need:
      From a dark (purple) cut four 3 1/2 inch squares and two 3 7/8 inch squares
      From a medium (hot pink) cut four 3 1/2 inch squares and two 3 7/8 inch squares
      From your background cut four 3 1/2 by 6 1/2 inch rectangles and four 3 1/2 inch squares
First we'll make four diagonal half squares with the hot pink and purple 3 7/8 inch squares. (You can find directions with diagrams for making diagonal half squares
by following this link.) Use one hot pink and one purple square for each pair.
Next we need four flying geese units using the background rectangles and 3 1/2 inch hot pink and purple squares.
To make your job a little easier, draw a diagonal line through the hot pink and purple squares.
Lay a hot pink square right sides together with a background rectangle, with the diagonal line running as shown here. Sew right on that diagonal line. Trim off the excess, leaving a z inch seam allowance. Press to the background.
   
Repeat this same step again with a purple square on the other side of this same unit. Press to the background. Make sure your rectangles still measure 3 1/2 by 6 1/2. This is called a flying geese unit.
   
Repeat this same step with the remaining rectangles, pink and purple squares. You need four flying geese units.
Sew the four diagonal half squares together like this
   
   
and then add flying geese to either side of that unit.
Next make two rows like this
   
Assemble as shown. Your finished block should measure exactly 12 1/2 inches.