Mag Chalkboard Paint: Paint a wall, have some craft activities to have her make castle/house/outdoors/etc pieces (modular ideas so she can build the castle in many different configurations). Also could use chalk to outline and draw.
Do's and Don'ts of Chalkboard Paint to Make a Design Statement
Chalkboard paint tips & tricks: There’s a method to applying chalkboard paint that will make your walls look their best. Make sure to heed these do’s and don’ts, from what surface to paint to how long you should wait between coats to which kind of chalk to use once it’s good to go.