Now that the five sections, A, B, C, D, and E, have been pieced and the edges trimmed, it's time to join them together to form one large piece.
The pattern lists the sewing order as:
A + B
AB + C
D + E
ABC + DE
Don't worry - it's not a math nightmare! This simply means that you first sew sections A and B together, then you sew the "A+B" piece to "C." D and E get sewn together, and then you sew all the pieces together, "A+B+C" and "D+E", to make the one piece. If you want it in mathematical format, (A+B+C)+(D+E) = Paper Pieced Union Flag.