My very first sewing project in home ec in 7th grade was making a gingham half apron and we measured everything by counting the squares on the gingham. It was really cool. I wish I could find a pattern for that apron on line. It was super simple. The skirt of the apron was gathered and the waistband/ties were really easy to attach.
I hope you have fun teaching your young lady how to sew. She will love you for the lessons and the memories will never leave her.