Sewing a Simple, Lined Bag With a Zipper
My daughter loves to put her My Little Ponies and Legos in containers and bags to have a quick, easy way to save them from her brother. I decided to make her a new lined bag using fabric and a zipper I bought at S. R. Harris since her collection of both My Little Ponies and Legos have been quickly growing. My mom uses light colored fabric to line bags so that it is easier to see inside to dig through the contents. With that thought in mind, I used a light purple cotton/Lycra knit for the lining. The outer layer is made of a light green woven fabric that is soft and thin, so I would guess that it is made of rayon. I used a separating zipper since it makes the construction of the bag much easier. Instructions for the lined bag are included below.
Fabric and Notions
Separating zipper, any size
Outer fabric, width equal to the length of the zipper plus twice the size of the seam allowance
Lining fabric, same size as the outer fabric

Steps
Step 1. Preparing the Fabric
Since I am at an age where I know that my mom is usually right, the first step is to wash the fabric. The second step is to iron it. The fabric used for this bag was very light weight and easily wrinkled so it is harder to tell it was ironed as the steps progress.
Step 2. Cut the Lining and Outer Fabric
To account for the seam allowance (I used 3/8") cut your fabric to be the length of the zipper plus the seam allowance multiplied by two. The length will be twice the desired height of the bag plus the seam allowance multiplied by two. In terms of equations:
width = length of zipper + 2 * seam allowance
length = 2 * desired height + 2 * seam allowance

Step 3. Adding the Zipper, Take 1
Place the outer fabric of the bag on a flat surface with the right side up. Place the zipper on the outer fabric with the upper edge of the zipper aligned with the upper edge of the outer fabric. The zipper should be upside down causing the pull on the zipper to be facing down.

Place the lining fabric on top of the zipper and outer fabric with the upper edge aligned with the upper edge of the zipper. The lining should be oriented with the right side down, facing the zipper.

Using a zipper foot, sew the upper edge of the zipper-fabric-sandwich together. The seam will be sewn blindly, but the zipper teeth should be easy to feel beneath the lining fabric.
After the seam has been sewn, fold the lining and outer fabric back so the zipper is visible and the wrong sides of the lining and outer fabric are touching. Iron along the seam to ensure the lining and outer fabric stay in place and to add a professional look. Ensure the iron does not touch the zipper teeth. The picture below shows the fabric ironed in place with the lining fabric showing. The next picture shows the outer fabric layer.


Step 4. Sewing the Zipper, Take 2 Separate the zipper. Open the recently ironed seam, causing the outer fabric and lining to no longer be sandwiched together. Place the raw, upper edge of the outer fabric on a flat surface with the right side up. Place the loose half of the zipper on the raw, upper edge of the outer fabric with the zipper's edge aligned with the raw edge of the fabric. The zipper teeth will be below the edge of the fabric.

Place the raw, upper edge of the lining on the zipper, with the edges aligned. The half of zipper that was sewn in the previous step will now be covered by the lining and no longer be visible. Using the zipper foot, sew the two layers of fabric and zipper together. Turn the layers of fabric inside out so the zippers are now visible. Iron the fabric along the seam without touching the teeth of the zipper with the iron.
Step 5. Sewing the Edges
Turn the fabric inside out so the wrong sides are now facing out. Fold the fabric so the zipper is aligned and the outer fabric is on one side of the zipper and the lining is on the other side. Sew one edge of the outer fabric and the lining, on the same side of the bag. The seam should go as close to the zipper as possible without sewing over it.

Sew the other edge of the outer and lining fabrics with the same alignment, but leave a gap of approximately one inch on either side of the zipper. The gap may need to be larger or smaller depending on the size of the bag. This gap will be used to turn the bag inside out to place the right sides of the outer and lining fabrics into their final positions.
Step 6. Almost Done...
Turn the bag inside through the gap so the right side of the outer fabric is showing and the right side of the lining fabric is visible inside the bag. Carefully zip up the zipper and sew the gap closed. Hand stitch the two sides of the zipper together at the separating end to ensure it does not fully separate when unzipping the bag. The stitch should be placed on the last zipper teeth, rather than after them. This is not absolutely necessary, but will eliminate the headache of aligning the zipper properly to re-zip it after being separated. If desired, hand stitch the lining fabric to the outer fabric in the lower corners of the bag in the machine sewn seam to keep the lining in place.

Step 7. Admire your hard work!