This unit engages students in a comparison of animals and plants that are extinct to animals and plants found today as theyexplore the effect of changes to an environment on the ability of animals and plants to survive. A KWL serves as a formative assessment of students’ conceptions of dinosaurs—a commonly known set of extinct organisms—and serves as a jumping off point for discussion of other organisms and their environments. Students consult multiple information sources to gather evidence of the effect of changes in an environment on organisms as seen through past and current examples. Students create a scientific notebook to compare examples of an extinct and a current organism and their environments, and argue for the effect of changes on the ability ofeach to survive.