Read the story of the Last Supper.
As reading children to role-play the story, from preparing the room, through to the washing of the feet and the institution of the Eucharist.
Make some references to the meal probably being a celebration of the Jewish Passover. Set up the table for the Last Supper to include some of the ritual foods used at the celebration of the Passover.
Explore the thoughts and feelings of the disciples preparing the room for the celebration. What food would they need to get ready?