Does your granddaughter still play with dolls? If she does this is a nice project -
https://thecottagemama.com/2014/01/b...nket-tutorial/
Perhaps someone known to your family is having a baby - she might like to make the smallest size quilt.
What about Christmas themed placemats or mug rugs?
I have also see some very simple book bags that are made from pretty pre-cut squares and lots of embellishments.
I’m not sure about her having a rotary cutter though!
It is wonderful that you are going to share your skills with your granddaughter - I long for the day when one of mine asks ‘Grandma, will you show me how to use your sewing machine?’