My daughter wears a size 8/10 RTW, and this skirt fits her perfectly. You might want to adjust for a smaller/larger size. (If you want a fuller skirt, you will need 3 to 4 FQs for the overskirt and 3 to 4 for the underskirt. If you want a longer skirt, you can use 3 to 4 FQs for each skirt and turn them longways or use longer yardage.)
If you are using FQs, which are approximately 18" by 22", you'll want to use pretty much the entire piece for the underskirt. Lay your underskirt FQs right sides together and stitch along both short (18") edges, making a tube of fabric. I trimmed the overskirt pieces to 15" so that there would be about 3" of the underskirt peeking out at the bottom. Stitch the 15" sides, and then serge all seams to keep things nice and neat. (I used 1/4" seams to make the most of the fabric.)
Here I've used yardage instead of FQs. I cut my underskirt to 18" by the fabric width, and my overskirt pieces to 14.5" (I didn't have quite 15") by the fabric width. You can see that the blue fabric is slightly wider than the pink fabric. Make sure to trim them to the same width- this is important later on.
With yardage, you will only have one seam for each skirt instead of two! I used a 1/4" seam (excluding selvedges, which I trimmed off) and serged to keep them neat.
Press the seams to one side and then hem your skirts. I used a simple, 5/8" hem.
Now comes the fun part. Pin your skirts together at the top edge (this is why they have to be the same width!), right side of the overskirt to the wrong side of the underskirt. Like so:
Stitch with a 1/4" seam and then press that seam open.
Now, turn the overskirt to the outside and press again. Your skirts will be attached at the top edge, both right sides up, with the seam enclosed between them.
Take your skirt to the machine and edgestitch the joined edge (optional.)
Now sew anther row of stitches 1" away from the first row. This forms the waist casing. Make sure to leave an opening for the elastic.
Open your skirts out and insert your elastic from between the two.
Once the elastic is threaded through, join the ends and stitch up the opening in the casing. Voila! Finished skirt!
I hope you like this simple little skirt. It's very easy to make and very quick. I think it took me about an hour, and I'm rather slow.
I'm off to sew some more, but I'll leave you with a sneek peek at what I'm working on now: