Making Sense of Evolution

Student Goals and Activities

A typical science unit for the 8^th grade students at Marquette School of Excellence includes model-based inquiry activities, labs, mini-lessons, reading and analyzing scientific texts (usually in tandem with a reading strategy differentiated for students), in-class discussions, activities, formative assessments and summative assessments. In this unit, students will be asked to analyze fossils of ancient organisms and create evidence-based models about how the organisms were adapted to their paleoenvironments. The ultimate goal is to get students to demonstrate their understanding of how morphological traits can tell us about environments, since environmental challenges and evolution are so closely linked.

Students will begin the unit by creating an initial explanatory model of an organism and its paleoenvironment. As the unit progresses, students will revisit these models at least two more times to include new evidence that they have learned through classroom activities. These initial models will provide information on preconceptions and misconceptions that students may have, informing the further development of sense-making activities. The models that students will be creating will be based on the example organism noted above, the woolly mammoth. In their model, students will be given a few clues (more to be given throughout the unit) that will help them explain what the paleoenvironment of the woolly mammoth might have been like based on fossil records of the woolly mammoth and their ancestors. The initial models are fairly bare-boned but can include particular prompts if desired. In the models used in my classroom, I would provide some scaffolding, such as headings for the types of evidence for which I would be looking.

Following the creation of their initial explanatory model, students will use a simple model to help them envision the unimaginable expanse of geologic time. This American Biology Teacher activity can be found through searching “Picturing Evolution through Geologic Time.” The activity addresses several challenges students face in comprehending geologic time including: (1) the meaning of a billion years ago or million years ago, (2) understanding when life forms first appeared on earth, (3) putting the time between events in perspective, and (4) clearing the misconception that major life forms only evolved in recent geologic history.³⁷ For each partner or group doing this activity you will need adding machine tape (6 m long), a metric ruler, Geologic time chart, and a list of key events. It is up to the teacher to decide how detailed students should be with geologic, atmospheric, and biologic events. Students may be given a prescribed scale to use (1 mm = 1 million years) or may be given the responsibility of determining the length and scale of the accounting tape. Additionally, students may be given list of key events without dates and then given the task to place these events where they think they belong. Once given the key events with dates, students will most likely be surprised by the differences between their initial thoughts and the actual placement of events. There are a variety of questions that could be asked during the discussion portion of this activity. Questions may include simply identifying when events occurred and comparing lengths of time between events. It is recommended that these scales be posted in the classroom and used throughout the unit for revision (perhaps adding additional events) and reference. Homework related to this assignment may include having students create their own, personal time scale for a personal connection to the lesson.³⁸ Another activity related to understanding the geologic time scale would be to have students chose a particular time period and create a brochure for potential time-traveling visitors to guide them. The brochure should include information on major geologic, atmospheric and biologic events that occurred during the chosen time period. Students may present their brochures in class depending on time constraints.

In terms of activities for learning about fossil formation, there is a wide variety available on the internet. Students in my classroom will experience activities that range from reading articles on fossil formation to hands-on activities, such as creating and analyzing trace fossils and other types of fossils. Students, in partners or small groups, analyze fictitious strata from different geographic locations with a variety of fossils in them and determine which fossils would make good index fossils. The main goals for activities centered on fossils include: (1) understanding how fossils are made, (2) understanding different types of fossils and what they tell us, (3) how scientists use fossils to correlate and date rock strata, (4) how scientists use fossils as evidence for evolution, and (5) how scientists use fossils to reconstruct ancient environments.

When having students utilize fossils to reconstruct ancient environments, it may be best to use a local record. The website www.paleoportal.org offers a wide variety of information on the local paleontology in all U.S. states as well as other supplemental materials found on the online version of the article which the next major activity is based upon. On www.nsta.org, you can purchase the entire lesson, “Using observations of fossils to reconstruct ancient environments.” Using the internet, students should research local fossil records. As a class, the various fossils can be organized into like groups. It is important to include groups that students may not be familiar with, such as vertebrates versus invertebrates. If possible, it would be ideal to have actual fossil specimens that are found in your area for students to use. If not, printing out pictures of these fossils will suffice. When organizing the fossils into groups, a variety of processes could be used, such as think-pair-share. Students must be able to construct sentences that explain why a certain fossil is a member of a certain group as opposed to another. They will then hypothesize the types of environments these organisms lived in based on their morphology. Students should back up their claims with evidence. When sharing out, it is possible that misconceptions will arise that you may have to address later in the unit. This may also offer a good opportunity for students to practice collegial discussion techniques utilizing sentence starters. Students will bring in the concept of uniformitarianism by looking at modern day organisms and their preferred environments to make inferences about the ancient environments in which the sample fossil organisms lived.³⁹

As a culminating activity (in addition to the final explanatory models created by students and revised over the course of the unit), students will combine their understanding of geologic time, fossils, evolution, and significant changes in Earth’s various systems in a literacy-based assignment. Students will use the example organism discussed above, the woolly mammoth, to recreate what its paleoenvironment would have looked like. Students will use fossil evidence from woolly mammoths and their ancestors in their reconstructions as well as evidence for evolution. Students will complete a RAFT writing assignment that asks them to take on a role, an audience, a particular format, and topic. The role, audience, and format can be tailored to the students in the classroom. However, the topic should be around the paleoenvironment of the woolly mammoth using evidence as noted above.