National Academies Summer Institutes for Undergraduate Education in Biology
Teachable Unit Framework
Title of Unit
Date and
Location of SI
Unit Developers &
Contact
Information
Context
Abstract
(< 200 words)
Rationale
Mountain West 2013
Boulder, CO
Kris Karsten, California Lutheran University, karsten@callutheran.edu
Catherine Kleier, Regis University, ckleier@regis.edu
Frank Messina, Utah State University, Logan, frank.messina@usu.edu
Theresa Rogers, California Lutheran University, terogers@callutheran.edu
Kristin Swihart, University of Colorado at Boulder, swihart@colorado.edu
Becky Williams, Utah State University Uintah Basin, Vernal, toxwilliams@gmail.com
Facilitated by: Stanley Lo, Northwestern University, stanley-lo@northwestern.edu
What kind of course is unit designed for?
First exposure to phylogenetic trees in general biology.
How long is unit?
2-3 classes of 50 min duration
When will the unit be used in the course?
First 1/3 of the course, depending on course level.
This unit and tidbit can be used or modified for basic biology as well as upper division courses.
Many students, and professional biologists, have trouble inferring correct genealogical relationships from phylogenetic trees. Even after students learn to construct phylogenetic trees, misconceptions remain. In order to let students recognize their misconceptions, we ask them to interpret two trees that have the same genealogies, yet have different arrangements. Students are meant to see that the orientation of the organisms at the tips of the tree is unimportant. Instead, they are meant to realize that the important information in the tree is the sequence of branching points, or nodes - which indicated different degrees of relatedness. This concept is tested multiple times in the exercise using various activities such as having students work in groups to transform statements about relatedness into a tree with the correct genealogy. They also can see that the ordering of species at the tips of the tree can be varied without changing the basic genealogy. We also have students critique the phylogenetic trees constructed by other groups to determine if the trees are correctly drawn. Finally, we have a summative assessment in which the students are shown four phylogenetic trees and asked to choose the genealogy that is not the same as the other three.
How did the idea for the unit arise?
Experience teaching a phylogenetic unit has demonstrated that students revert to misconceptions when reading phylogenetic trees
Why was this topic chosen?
Despite student competency on the teaching day they learn to read trees, many students do not retain the ability to read trees and revert to misconceptions
What misconceptions or difficult topics are addressed?
Students often look at spatial proximity to determine relationships instead of identifying the most recent common ancestors
Teachable Unit Framework 1

National Academies Summer Institutes for Undergraduate Education in Biology
Teachable Unit Framework
Learning Goals: what students will know, understand, and be able to do; includes content knowledge, attitudes, & skills
Learning
Outcomes:
Student behaviors or performances that will indicate they have successfully accomplished the goals
Students will understand phylogenetic trees as representations of evolutionary history
1.
2.
3.
4.
Construct a phylogenetic tree using character data
Understand that phylogenetic trees are hypotheses about evolutionary diversification of organisms
Correctly interpret phylogenetic trees
Use information from phylogenetic trees in an applied context
1.
Define shared, derived characters (synapomorphies) and work example problems during which trees are constructed using character data
2.
Evaluate which tree more likely represents true evolutionary history based on parsimony
3.
Identify ancestral vs. derived characters
4.
Demonstrate that polarity of characters is relative with respect to which ingroup is being considered
5.
Correctly interpret phylogenetic trees
6.
Identify the most recent common ancestor of a given group
7.
Draw trees that show equivalent genealogies
8.
Define and identify monophyletic, paraphyletic, and polyphyletic groups
9.
Accurately determine relative timing of evolution of characters of interest by mapping traits onto a tree
10.
Make decisions in a conservation biology case study based on evolutionary relationships
11.
Give an example of an application of phylogenetic trees and explain why determining evolutionary relationships is critical within the context of that example
Active Learning
How students will engage actively in learning the concepts
Assessment
How teachers will measure learning; how students will selfevaluate learning
Diversity
How the unit is designed to include participants with a variety of experiences, abilities, and characteristics
Teachable Unit Framework 2

National Academies Summer Institutes for Undergraduate Education in Biology
Teachable Unit Framework
Activities outside of class:
Students will have already constructed trees in a lab setting
Pre-class reading on phylogenetics
Activities in class:

Before the tidbit, students learn to construct trees though worksheet and group activities. After the tidbit, students learn to use an outgroup to polarize characters as either ancestral or derived and they learn to identify monophyletic, paraphyletic, and polyphyletic groupings. The latter are supported by clicker questions where students identify characters as ancestral or derived with the character highlighted and the ingroup circled. The ingroup is then changed in the next clicker question, but the character is not. The change in ingroup is chosen to change the polarity of the character from ancestral to derived or vice versa.
Activities during tidbit:

Clicker questions designed to identify common misconceptions about reading trees

Clicker question as formative assessment throughout

Further formative assessment in the form of a think-pairshare to allow students to teach each other and evaluate their understanding of the subject

Tree drawing competition
Pre-assessments:
Worksheets requiring students to construct trees in the first part of the unit
In class assessments:
Formative:

Clicker questions designed to identify common misconceptions about reading trees

Clicker question as formative assessment throughout

Further formative assessment in the form of a think-pairshare to allow students to teach each other and evaluate their understanding of the subject

Tree drawing competition
Summative:

Last clicker question requires all three learning objective skills
Post tidbit/class assessments:
Homework (Practice exam questions)
Exam questions
Inclusive teaching principles
• All students involved in work in small groups
• Think pair share allows students to demonstrate their knowledge and reasoning skills to fellow students in a low-pressure environment
How people learn
• The same concept is presented in multiple visual formats, students translate from written instructions to diagrams, and physically draw and manipulate trees
Teachable Unit Framework 3

National Academies Summer Institutes for Undergraduate Education in Biology
Teachable Unit Framework

Additional summative assessment clicker question that requires all three learning objective skills
25–30 min for tidbit
Time (min) Learning Outcome(s)
1.
Correctly interpret phylogenetic trees
2.
Identify the most recent common ancestor of a given group
3.
Draw trees that show equivalent genealogies
Activity/assessment
Formative:

Clicker questions designed to identify common misconceptions about reading trees. The first set of clicker questions shows that some will read the same tree and interpret it differently.
At the slide with the two trees side by side, explain again how to interpret trees, then move on.

Further formative assessment in the form of a think-pairshare at the horse phylogeny to allow students to teach each other and evaluate their understanding of the subject
Explanation, notes, suggestions, tips
There are many tools and labs available and tested that help students learn how to construct trees in the lessons preceding this tidbit
Phylograms should also be covered before this tidbit http://www.tree-thinking.org/
Teachable Unit Framework 4

National Academies Summer Institutes for Undergraduate Education in Biology
Teachable Unit Framework
Enter approx. class time for learning activity preparatory material presentation
Enter approx. class time for learning activity
#1
~90 min
5 minutes to choose closest frog relative in two clicker slides
Enter approximate time for additional learning activities and associated class
Work/preparatory materials
Enter approximate time for post-activity summing up or transition
10 min to think-pairshare on the horse phylogeny
10 minutes for tree drawing competition
20 minutes to write practice and exam questions
Add additional activities information as needed for the unit.

Tree drawing competition: Ask students to produce as many trees as possible that illustrate the same phylogeny based on the written relationships of apes.
Restrict competition to 3 minutes.
Summative:

Last clicker question requires all three learning objective skills

Homework (Practice exam questions)

Exam questions
Teachable Unit Framework 5

National Academies Summer Institutes for Undergraduate Education in Biology
Teachable Unit Framework
(other files and information needed/helpful to teach the unit, including files for papers from which original data for class activities is taken, supporting information for the instructor, handouts, in class activities materials, assessments with answer keys, homework assignments, etc.)
Group 3 Evolution Tree Thinking.pptx file tree thinking website: http://www.tree-thinking.org/
We recommend that the instructor bring in a mobile to demonstrate the mobile analogy.
Novick, L. R., Stull, A. T., & Catley, K. M. (2012). Reading phylogenetic trees: Effects of tree orientation and text processing on comprehension. BioScience, 62, 757–764.
Baum, D. A., DeWitt Smith, S., & Donovan, S. S. (2005). The tree thinking challenge. Science 310, 979–980.
(Facilitators, others who gave input, information, etc.)
We thank Stanley Lo, Renee Dawson, Katy Richards-Hrdlicka, and Brian Couch for facilitating.
We thank Michelle Smith, Maggie Richards, Susan McGrath, Asim Auti, Tammy Maldonado, Scott Franklin,
Lauryn Benedict, Les Sommerville, Katie Mouzakis, Michael Gustin, Kathleen Mathews, Dereth Phillips, Bernice
Aguilar, and Terri Stoner for recommendations on drafts.
Teachable Unit Framework 6