In this activity, students will use research to develop an operational definition of life and then use the fundamental criteria for life to examine simulated extraterrestrial soil samples for signs of life. Materials A pair of objects, one living (such as an insect or plant) and one non-living (any inanimate object, preferably one not made from once-living material such as wood or leather) An outdoor area to investigate, or images of a variety of living and nonliving things Hand lenses Criteria