In this project you can talk about the different hemispheres of the brain and the sulcus and gyrus.
Once the outside is done you can open the brain up and add something on the inside as well. As simplistic as the "right brain" "left brain" idea is you can start with that as inspiration. Putting something like a paintbrush on the right side and letters or numbers on the left side.
Or you can leave the space empty and fill once it is fired.
It is a great idea that can take a number of forms! Enjoy creating!