I also do coil and pine needle baskets (Bunki is the expert on pine
needle) - I have them do a flat sample about 3 inches wide to demonstrate
beginnings, splicing and ending skills before I cut off that "big " piece
of basket core for them. They have to have their design graphed out on
paper and approved and show me the materials they are planning to use.
The basket comes at the end of the year and soothes the savage beast of
all that stress, especially for seniors - we coil and chat and listen to
music - plus for teachers very little clean up. Masking tape is good to
prevent sore finger tips - or those rubber finger things that sorters use.