I mentioned a while back I had cut up a pair of men's corduroy pants for yardage to make the girls some things. The pants were cuffed so I cut the bottoms off below the knee, opened the inseams and used  one opened leg for a skirt front and one for the back of a simple straight skirt for Tess.  Its basically just a rectangle with a casing at the top.  

For Abbie I made a pattern off a skirt she already had that fit well (size 2-3)and added a smidge all around for growth:

Cut two rectangles 9" high and 8"wide for the yoke.  There are two rectangles of 8" high and 30" wide for the skirt bottom.   (I use a half inch seam allowance when I sew and factored that in)  

Run a long straight stitch across the tops of the skirt pieces taking care not to backstitch at the ends.  

for each side (front and back) gather the skirt top by pulling one thread, fitting the width of the skirt piece to match the yoke piece. 

Pin and sew yoke front to skirt front

Pin and sew yoke back to skirt back

sew together front and backs at the sides

turn under a 1" casing at the waist and stitch down leaving an opening for elastic.  

Turn under hem at bottom and stitch. 

Pull elastic through waist and sew together.  Handsew opening shut. 

Call it done. : ) 

Now the proper way to do this would be to sew the yoke front and back together, then sew the skirt front and back together.  Then slip the yoke into the skirt right sides together,gather, pin, and sew.  It just takes longer that way.  You choose.  

For more polished results consider adding more seam allowance to the sides and do them up in French seams.  Its much much easier than it sounds.  Simply sew the seams with the WRONG sides together using a very narrow seam allowance, then turn inside out and press.  Sew the seams as usual with right sides together.  Turn it right side out and press again.  Now you have nice neat seams with no ragged edges.  : )