by Jennifer Broo and Jessica Mahoney
Curriculum team: Julie Bokor, Sean Moran, Cheryl McLaughlin, Bruce MacFadden
The development of these 3 lessons is supported in part by the following:
• Frances C. and William P. Smallwood Foundation
• Science Education Partnership Award, National Center for Research Resources, part of the National Institutes of Health – Grant No: 1 R25 RR023294-01A2
• National Science Foundation Grant 0966884: PCP PIRE – Panama Canal Project | Partnerships for International Research and Education
LESSON ONE: Exploring the Geologic Time Scale via Changes in Fossilized Horse Teeth in Response to Co-evolution of Plants
As an opening activity the class will be presented with a slide show of illustrations representing the physical landscape of each of the 5 epochs that will be explored in this lesson. As a class students will be asked to make observations about the types of flora present in each epoch. Next, in collaborative learning groups, students will measure and sketch physical characteristics of fossilized horse teeth from a study set provided by the FLMNH. Each group will produce a graph that summarizes the trend between age of the fossil and length of the tooth. Plant information cards summarizing each epoch will also be provided to each group. Guided analysis questions will allow students to develop an explanation for the change in horse teeth in response to plant evolution.
LESSON TWO: Examining Intraspecies Variation and Changes in a Single Horse Population
In this lesson students will be provided with a collection of horse teeth from the same population. Students will be asked to take HI measurement data (same procedure as Lesson One) to determine if this collection of teeth represents individuals from the same species. Students will also be asked to use the graphs produced in Lesson One to determine which species this population likely belonged to. Additionally, students will determine if there is intraspecies variation in this population, using an embedded horse tooth variation guide in the student page: Examining Intraspecies Variation and Changes in a Single Horse Population. Finally, students will begin making predictions on what could happen to horse teeth in future generations if plant life drastically differed again on Earth.
LESSON THREE: Proposing Changes to Orthogenesis and Communicating Evolution in Museums
Students will be presented with a current problem observed in the majority of natural history museums in which orthogenesis is primarily used to display the evolution of horses. The use of orthogenesis, rather than the widely accepted branching phylogenetic tree, often leads to misconceptions about evolution amongst visitors of the general public to such exhibits (MacFadden, et. al. 2012). Teachers can chose to provide students with a fictional letter from the curator of a natural history museum requesting their help with this problem or have students complete a close read of the paper by MacFadden and colleagues (2012) to explore this issue. Students will then use their fossil data graphs from Lesson One in addition to information about ancestral horse species to complete a computerized infographic proposal to summarize how the fossil records clearly show a branching phylogenetic evolution of the horse.