Well, hard, maybe not, but easy, not that either.
Here is the lampshade she needed covered. A side view and a top view.
Then I used a leftover piece of curtain lining and cut one out and tested it against the lampshade.
It kind of reminds me of a gored skirt pattern.
I needed four pieces to go all the way around the shade. I cut them and sewed them together using a 1/2" seam, then tested it on the shade. My pattern was a little too big, so I took all the seams in another 1/2" from the previous seam and trimmed the old seam off. That worked like magic!
Finally, I felt like the top and sides were fitted as good as I could get them, and I turned up the bottom for a finished edge there.
The last step is to use a fabric glue and glue the top and bottom edges to the shade.
And here is the final product!