This is an exciting moment for you and for her! I'd be a bundle of nerves!
Short list I've kind of used with my grands:
1) How to thread the sewing machine. Made the grands feel very competent and gave them an early success.
2) Bobbin insertion/winding
3) Sample straight stitching where you show her tension/out of tension stitching.
This will give her an idea of when to ask you about a tension problem.
4) Guiding fabric, protecting your fingers.
Safety first!
Remind her not to watch the needle go up and down while sewing! For straight stitches, it doesn't go anywhere but up and down! It took me several years to realize that I was watching the needle instead of guiding the fabric...
5) Mistakes happen, thus, the importance of owning a seam ripper.
There is no 'undo' button on any sewing machine!
A seam ripper is like the pencil on an eraser - there to help you fix mistakes. Right now I have at least 5 well used seam rippers at my various sewing spots.
Safety! A seam ripper is a SHARP instrument and, can, indeed, poke your eye out. This is not idle or humorous advice, it's the truth; I grazed my right eyebrow.
6) Cutting: Stress safety.
Measure twice, cut once. If it were me, I'd just have her cut some scraps until she gets the hang of cutting. Cutting mistakes can be, shall we say, discouraging. (for safety reasons, i don't let my grands cut fabric.)
Mostly, you will have to be patient. Enjoy!