ruth has hit the nail right on the head. i would add just one word of caution.
flannel is popular for rag quilts because it frays so easily. soooo, if i use flannel for a regular quilt, i sew 1/2" seams using an overlock stitch instead of the usual 1/4" straight stitch. i also quilt in the ditch of all seams to add stability.
these precautions may not be necessary but waaaaaaaaaaaay back in the beginning of my quilting adventures i used a 1/4" seam on fabric that frayed more easily than the others. it fell apart in the first wash. :shock:
sooooooooo ... i take no more chances.