Unwind entire length of A and fold in half. Cut across at fold to divide the yarn into 2 equal lengths.
Fold each yarn length in half again, but do not cut.
Pin folded ends to flat surface. Separate lengths so that you have 4 strands. Pin the end of each strand to flat surface.
You will be weaving over and under the A strands with B, unwinding the ball of B as you work.
Beginning at the folded end of A strands, loosely weave B under the first strand, over the second strand, under the third strand, and then over the fourth strand to make the first row of weaving. Then take B around and under that fourth strand and weave back across the A strands, going under the strands that you went over in the previous row and over the strands you went under on the previous row to make the second row of weaving.
Continue weaving in this way until all of B has been used.
With sewing needle and thread, sew a few stitches through each yarn intersection on the first and last rows of weaving to secure the yarn in place. Sew a few stiches through each yarn end and sew to the Scarf to secure.