Using CER to Deepen Thinking

When I started using the Claim, Evidence, Reasoning framework last year, little did I know the transformative power it would have in all aspects of student learning. Opportunities to incorporate scientific argumentation in the classroom continue to present themselves.

The last time I taught College Biology was pre-CER for me, so it's been exciting finding ways to incorporate it into the methods I've traditionally used with this class. One recent shift was a speciation activity from previous years. The original lesson asked students to plot data about the location of various sub-species of the California salamander, Ensatina. Students would then answer questions about the patterns that the sub-species created and eventually be "led" to the possibility that speciation had occurred. Here's a LINK to the original lesson from ENSI. I like that the activity is based on actual research on ring species, initiated by Robert Stebbins from UC Berkley in the 1940's. However students never really puzzled over the data as much as would have liked them to. So, I decided to apply the principles of CER to the activity, hoping to see more critical thinking.

Image from http://evolution.berkeley.edu/evolibrary/article/0_0_0/devitt_02

To start the activity, I shared the story of the Ensatina salamander species with the students. I showed them photos of what the sub-species look like and discussed the history of the research that has benn done on the species. Students then used the data and map from the original activity to plot the locations of the salamanders. At this point, instead of answering scripted questions, I tasked the student teams with (1) Writing a CER argument addressing the question, How did speciation of the Ensatina salamanders occur in California? (2) Diagramming a whiteboard model to support their argument. Remember, the students had no knowledge of the actual scientific result of this research.

The discussions teams had while developing their CER and whiteboard models were exactly the type of thinking I was hoping for. Students debated which sub-species was the most ancestral, why salamanders in different areas of California looked so different, and applied topics from class such as disruptive selection, habitat isolation, and hybridization. Each of their models and arguments ended up being a little different. Since we didn't have time to run an official white boarding "class conference," I asked every team to create a video describing their CER with the whiteboard model as a prop in the video.

This wasn't the end of the activity, however. I wanted the students to evaluate each others' arguments. Also, I no longer give points for group work, so I was searching for a way to assess my students individually on this topic. What I decided to do was this: Each student watched three CER videos from teams other than their own. After watching the videos, they critiqued the arguments discussed in the videos by responding to the prompts below.

1) Compare and contrast the speciation arguments in the three videos you watched.

2) In your opinion, which team developed the strongest argument? Why? (Discuss the qualities of all three arguments in your explanation.)

3) Describe two additional pieces of information that would have improved all the groups' arguments. In other words, if you could request that the original salamander scientists provide you with more data or information, what would have been helpful to know to support the arguments?

The results were outstanding. Students dug into the arguments of their peers and provided very insightful analyses of evidence.

Here are some excerpts of student work from the peer critique:

I was extremely happy with the outcome of this CER lesson. Not only was the content of the course reinforced, but students participated in powerful science practices. Double win!