Table 1.

How do small things make a big difference? Unit overview.

Lesson	Title	Description
1	How did the tree of life change through history?	Students learn about the nature of science as they examine how and why the tree-of-life model has changed through history.
2	What is the current model of the tree of life?	Students focus on the current molecular three-domain tree of life as they read about Carl Woese's discovery of archaea and examine simulated DNA sequences to model how molecular evidence can be used to determine evolutionary relationships.
3	What are microbes?	Students define the term “microbe” and learn about the diversity of microbial shapes, sizes, domains, habitats, and metabolic properties through a video and discussion, an activity on microbial scale, and constructing a microbe mural.
4	What does a microbial ecosystem look like?	Students explore microbial ecosystems by developing and manipulating a model of nutrient cycling in a Winogradsky column.
5	How do microbes interact with humans?	Students are introduced to the diverse microbial communities that live in and on humans by reading adapted primary literature and popular science news articles and by developing scientific models.
6	What can happen when my microbiome is disturbed?	Through a case study based on a published scientific paper, students analyze data to investigate effects of a disturbance to the human microbial ecosystem.