Lesson 2 Building a Time Line – We investigated how fossil records provide evidence of the existence, diversity, disappearance, and change of many life forms throughout the history of life on Earth. We explored the sequencing of events preserved in the geologic record. We used models to observe time phenomena and analyze and interpret rock strata in the fossil record to provide relative dates. Then we constructed scientific explanations based on evidence gathered and an understanding of the principles of relative-age dating.