Abstract

The concept of geologic time can be difficult for students to grasp because of the vast scale of the Earth's 4.56-billion-year biography. This hands-on, minds-on activity highlights events during the Cenozoic Era through a card-sort activity based on the history of horses and their ancestors. Twenty-one cards cover the following topics: Epochs of the Cenozoic, data on equine ancestor species, climate and plant data, additional fossil data, and significant Cenozoic events. The cards are presented to the students in random order with some background on horse ancestors and the geologic time scale. Minimal directions are given so the students can use their creative abilities and critical thinking skills to align the data to the geologic time scale. Guiding questions encourage discussion of how horse ancestors, who were small forest dwellers and browsers, could evolve into the large grazers we know today.

Outcomes comprise the students' understanding of horse ancestors' place in space and geologic time by studying the changes in climate and corresponding evolutionary changes. Additional learning objectives are contextualizing geologic time and promoting students' ability to analyze different data sets and understand how they relate.

Context

This activity can either stand alone or be part of a more extensive Horse Tooth Laboratory experience, in which students study 3-D-printed fossil horse teeth. I have taught it both ways for undergraduate STEM and non-STEM majors.

Why It Works

As an in-class activity, students work in collaborative groups to relate the horse ancestor data to the geologic time scale. A discussion follows of the student sorting results. It is a fun, high-energy exercise with interesting student observations and, through a one-minute report, has from my qualitative observations met the learning objectives. Students remember this activity and say it is a highlight of their class experiences. The card-sort activity also can be given remotely with a discussion to follow.