The great diversity of multi-celled life on Earth today, how this diversity came to be, and the relationships among living things are the major topics of this module. 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.
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. 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. Students conclude this lesson by placing major innovations and extinctions on a timeline, learning that the majority of lifeforms with which they are familiar arose in the very recent past, relative to the age of the Earth and the age of the universe. First, they explore the variation inherent within species, measuring and comparing their own hand spans, and learn that each individual within a sexually-reproducing species is unique.