In this activity, learners combine two substances (plaster of Paris and water) to make a cast of an object's imprint in clay. Use this activity to introduce learners to how scientists and detectives can use plaster casts to preserve animal tracks, tire tracks, or footprints left in soft dirt or mud. This activity, located on page 2 of the PDF, is a take-home version of the display of the same name in the Crime Scene Chemistry unit in OMSI's Chemistry Lab. This is one of three activities in the Take Home guide for the Crime Scene Chemistry unit in OMSI's Chemistry Lab. The PDF includes two additional activities: Latent Prints and Invisible Ink.