Slowly add water while vigorously stirring until the mixture is about as thick as melted ice cream. Pour and wait. Slowly and carefully pour your mixture into the animal track. The cardboard circle will act as a form to hold the liquid plaster in place until it hardens. Wait five to seven minutes until the plaster just begins to harden.
Students can inscribe their initials and date in the slightly-soft plaster with a twig or pencil.
Wait at least 15 minutes for the plaster to harden before they pick up the cast. Back in class, when the track cast is completely dry, students may wash off clinging dirt with water and smooth the track with sandpaper and paint or shellac the plaster to improve appearance and prevent crumbling. Learning to identify animal tracks and how to read the stories told by animal tracks can be a fascinating hobby for people of all ages. The following books are key references for trackers. Pandell, Karen and Chris Stall, 1981.