Cladistics provides students with a visual introduction to classification of organisms by their physical characteristics.
Students are familiar with family trees. Using family trees as the prior knowledge hook, students are guided through the creation of a cladogram. The cladogram will be used to establish a family tree for T-Rex so students can use the evidence to infer what T-Rex tasted like.
Investigation Summary & Standards
Students will create a cladogram (SP2 Developing and Using Models) analyzing the physical relationships of prehistoric and current organisms. (MS-LS4-1 Analyze and interpret data for patterns in the fossil record that document the existence, diversity, extinction, and change of life forms throughout the history of life on Earth under the assumption that natural laws operate today as in the past.)
Students are working as scientists, specifically cladists to collect data they can then use to discover the evolutionary relationships by examining the common ancestry as defined by physical characteristics. (SP3 Planning and Carrying Out Investigations) (MS-LS4-2 Apply scientific ideas to construct an explanation for the anatomical similarities among organisms and between modern and fossil organisms, to infer evolutionary relationships.)
Fossils tell us more than what organisms lived on the planet but where they lived and how they are related. (MS-ESS2-3 Analyze and interpret data on the distribution of fossils and rocks, continental shapes, and sea floor structures to provide evidence of the past plate motions.)
Students will take notes as they research the physical characteristics of organisms so they can write a short summary of their findings and use evidence to support their answer to the lesson question - What did T-Rex taste like? (SP4 Analyzing and Interpreting Data) (SP6 Constructing Explanations and Designing Solutions) (SP7 Engaging in Argument from Evidence) (WHST.6-8.10 Writing routinely over extended time frames (time for reflection and revision) and shorter time frames (a single sitting or a day or two) for a range of discipline-specific tasks, purposes, and audiences.)
Students will be using an interactive website - What Did T.rex Taste Like? developed by the University of California Museum of Paleontology.
Connecting to Prior Knowledge
Classification of organisms and the creating of cladograms are new concepts for middle school students. To help students prepare for this lesson, I begin with making connections to prior knowledge to develop hooks for new information.
Classification is an important tool used by scientists to organize the the millions of organisms. Imagine a telephone book that lists all the numbers but in a random order. The phone book would be impossible to navigate. Scientists estimate that there are more than 10 million organisms that have inhabited the Earth. Using a cladogram helps to organize organisms by their physical characteristics.
The following images are a sneak peak from the website. I share these with students to help make connections to prior knowledge.
When family trees are created, we start with the oldest ancestor at the top and show all the descendants of that ancestor.
When we look at life's common ancestors, we will start with the most current ancestor and work backwards.
Students in Action
In this lesson, the students have the independence of researching questions using an interactive website format.
Prior to beginning their research, students are given a list of vocabulary suggested by the website - Amniotic egg, Bipedal, Bony skeleton, Common ancestor, Genealogy, Hypothesis, Lineage, Most recent common ancestor, Quadrupeal, Tetrapod, and Vertebrate . I provide the students with the list of words without the definitions to be added to their science journal using the Cornell Notes format.
Students are guided through the website in search of answers to What Did T-Rex Taste Like? Features Table. Students are also given a graphic organizer to collect information they will need to write their final report.
I share a few instructions with students to help them navigate the website.
First, the website will not allow students to advance until they have seen all the information connected to the current page. This feature creates the expectation that students will need to read and evaluate all information provided in order to fully understand the content and answer the questions.
The next button does not appear until the student has viewed all parts of the page.
In this video, I examine student artifacts of learning for this lesson. Students are expected to support their findings to other scientists by citing text-based evidence, in this case specific details from the website in answering the question - What Did T-Rex Taste Like? Take a look at the collection process where students develop vocabulary, and gather evidence to complete their report.
A Close Look at Student Work Samples
Student Work Samples (Resource section)
Students' connections for this lesson are quick and easy. All students agree that it is likely that T-Rex tasted like chicken.
We discuss how an excellent journal response to the question, "What Did T-Rex Taste Like" must include specific references to common physical characteristics from their Features Table.