Teaching students about the nature of science is a goal set out by the Next Generation Science Standards (NGSS), but this goal can be a challenge to meet in the classroom. Project NEURON developed a curriculum unit on microbial ecology which opens with a lesson to help address this challenge. In the lesson, students work in groups to examine how models of the tree of life have changed throughout history. The activity supports exploration of concepts such as: new technologies advance science, science is subject to change based on new evidence, and science is a result of human endeavors. In the presentation, we will share the goals and development process of the lesson and also provide time to participate in the student activity.