Many monuments and artifacts around the world are made of materials, like limestone, that are susceptible to deterioration from environmental factors and especially pollutants like acid rain. In fact, many ancient artifacts have eroded more in the last 20 years than they have over the past 2000 years. One example is the Great Sphinx of Giza whose head was carved from solid limestone. -- In this activity, students are given cat's eyes, seashells from Hawaii, to represent a limestone artifact. Both Cat's eyes and limestone are composed primarily of calcium carbonate. When calcium carbonate is exposed to even a very weak acid, it decomposes and dissolves. Students make observations and take measurements of acid rain and the sphinx tdct their "Sphinx" (the Cat's Eye shell) and then carry out an experiment in which they expose it to acid rain (vinegar) and then measure and observe the artifact again to see the effect(s). -- Students learn about effects of pollution, physical and chemical properties, measuring, using a balance, chemical reactions, and science process skills. A second activity demonstrates how acid rain can be formed from nothing more than water and the students own breath. -- Includes: Cat's Eyes, vinegar, photo of Cat's Eyes, petri dishes, plastic forceps, hand lenses, bromothymol blue, and instructions. Materials required but not included are balances, rubber bands, straws, and plastic or paper cups. -- Enough materials for a class of 30 working in pairs.