At this point, there's not much left to do before the backpack starts to come together. Both sides of the lining will have pockets. The back will have a large laptop-sized pocket and a zip pocket just like the top pocket on the front. The front lining will have three pockets.

So we have to do the same scary thing we did to the front of the backpack:

1. draw a rectangle on the wrong side of a zipper pocket lining piece
2. pin in place right sides together on the large lining piece
3. sew the rectangle
4. cut a slit along the length with Ys going into the corners cut at short ends
5. push pocket fabric through this hole and press the seam all nice
6. attach zipper (I use Fabri-Tac to baste it)
7. topstitch around zipper to secure
8. flip it over and sew the other zipper pocket piece to the first piece to make a pocket