Evolution of Life Module

The great diversity of multi-celled life on Earth today, how this diversity came to be, the processes that shape diversity, and the relationships among living things are the major topics of this module.

The Lessons

The first lesson, Introduction, assesses students' ideas about the diversity of life and how it became diverse. Students leave at the end of this day with a scavenger hunt assignment to collect samples and evidence of living things. This assignment extends throughout the course of the module and helps students begin to comprehend the great diversity of life and its evolutionary relationships.

The second lesson, How Diverse is Life?, defines the vast scope of life's diversity. Students begin by exploring the range of different environments in which living things are found. They gain an appreciation for the diversity and abundance of life by making estimates of worldwide species richness. An Extension Activity [not required] allows students to explore the concept of biodiversity through a microscope lab. Finally, students work with a biogeography database to examine the distribution of life on land, arriving at the conclusion that life is not distributed randomly on our planet.

The third lesson, Life's Diversity Over Time, focuses on the changing distributions of living things, the relationship between these changes and geologic changes, and changes in the types of living things over the history of life on Earth. An Extension activity [not required] addresses relative and absolute dating techniques, helping students learn "how we know what we know" about when extinct organisms lived. Students conclude this lesson by placing major innovations and extinctions on a timeline, learning that the majority of life forms with which they are familiar arose in the very recent past, relative to the age of the Earth and the age of the universe.

In the fourth lesson, How Does Life Evolve?, students examine the processes that have produced the vast diversity of living things in the past and today. First, they explore the variation inherent within species, measuring and comparing their own hand spans and learning that each individual within a sexually reproducing species is unique. Next, students examine the sources of that variation, studying mutation and recombination and developing an understanding of genetic variability in species. Selection upon these individual differences is the focus of the third activity. Students explore advantageous traits in a predation exercise and learn how competition for finite resources leads to selection pressure. The fourth activity illustrates the effects of natural selection upon gene frequency in a population, using the example of the peppered moth. . The fifth activity summarizes the previous activities from Lesson 4 and introduces speciation.

In the fifth lesson, How Are Living Things Related?, students explore how scientists determine evolutionary relationships among living things. In the first activity, students are introduced to taxonomy and how classification itself has changed over time and continues to change. Next, students explore how morphological features provide clues to evolutionary relationships, and learn about the limitations to this approach. The lesson then turns to the use of molecular evidence to determine evolutionary relationships. Finally, students work with a phylogenetic tree, using the same taxa they have explored in the scavenger hunt from the beginning of the module, to illustrate the great diversity and evolutionary relationships among living things.

The module concludes with the sixth lesson, Closing, which assesses students' understanding of major concepts from the module by asking them to complete a concept map and a paper and pencil test.

The Evolution of Life curriculum successfully ties together biochemistry, cell biology, ecology, and genetics by exploring all of life through the lens of evolution. Lessons are well planned to the last detail, and the integration of technology and scientific reasoning skills is masterful and effective. My students loved the computer-based explorations!

- Julie Reis, Abraham Lincoln HS, San Francisco, CA

What my students really liked about the Evolution of Life Module was the number of hands on activities that they got to do. As a teacher I liked the variety of activities and lessons, as well as having all the pictures, diagrams and activity guides available on my computer to place into my daily presentations to the class.

- Dean Munkers, Ukiah School, Ukiah, OR

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