In a study of fossils, fourth graders have learned that not only bones and teeth can become fossils. In fact any evidence of life long ago is considered a fossil including animal tracks and the imprint left behind from a shell. We decided to create our own mold and cast fossils in the classroom using clay, shells and liquid glue. Students first made the fossil mold in the clay using a shell coated in petroleum jelly and then filled the mold with glue to create the cast fossil. Once the glue dries, students will remove it and observe their cast fossils.