Spray with the clear finish, inside and out, and allow to dry Very completely. We bought new bottles of acrylic paint, and considering the small amounts of paint necessary, some of the dibs n' dabs I had at home might have been sufficient. My role in this amounted to cleaning the brushes before the paint got too crusty on them. You can buy matching saucers, but that will make the gift harder for the child to carry.
Teachers are pretty creative about such matters.
Instead of painting images that would remind the teacher of her, my daughter chose to paint things related to the teacher. This is the end of her 6th grade year, and she made these for some other school staff, too, as a parting gesture. If you make several, it does take the better part of an afternoon, and it's a very good Outdoor project in good weather. Make sure to have enough pots that the child can keep one. There were old towels placed between the pots to prevent breakage.