Even though this unit is primarily about common ancestry, it is the background of the dinosaurs that keeps it interesting for students. Students have a lot of interest in how the dinosaurs went extinct which provides a great setting to show students how scientists use fossil evidence to develop and support their theories.
I begin this lesson by asking to list everything they know (or think they know) about the extinction of dinosaurs and how they know that information. This is easy to organize in a T-chart with the heading What You Know on the left and How You Know It on the right. I have students work as a lab table to complete this task. This Example - Extinction of Dinos T-Chart provides an idea of how this may look, however, you could also add in a place for students to write questions they have/things they wonder as many students pose questions during their discussions.
With the way I use HHMI Biointeractive, you may think that I am paid to endorse their product! Once again, they have put together a fantastic video that explains how scientists have been able to support the asteroid theory using evidence found in the rock strata.
This video can be shown in one sitting or broken into smaller segments as there are natural breakpoints approximately every 10-15 minutes which allows for a great deal of flexibility.
I love the opening quote of the video and I make sure to pause the video and give students enough time to read it as we will revisit it in the wrap-up of this lesson.
I am not a huge fan of making students answer questions as they watch videos, I think they miss a lot of information and opportunities to make personal connections with the information as they filter looking for specific answers which lessens the video experience. However, I do think students need some guidance to focus on what you are hoping to get out of the video. I use the Video Notes guide, which is really just a T-chart (surprise!) that requires students to record the evidence that scientists recovered to support the asteroid theory and the conclusions drawn from that evidence. This open ended format allows students to pay attention to the video with a focus on the information that supports the goals of the lesson. I pause the video at key points in the beginning until students "get in the groove" of noticing the evidence. This Example of Video Notes provides a look at what students may find throughout the video.
I also pause at good discussion points, I cannot help myself - it takes me twice as long to show a video but I know that the students get the most out of the experience as I make it impossible to just "veg out" during the video. I especially like to point out when scientist develop new questions based on the discovered evidence. This is something that science students do not naturally do - they will do as instructed and follow a procedure to answer 1 question but they will not normally "create more work" for themselves by asking additional questions. This is one area that, I feel, needs to be addressed in the current science classroom. Putting students in charge of their learning, allowing them the freedom to investigate additional questions that arise and providing them with strong models is one way to improve their ability and willingness to go deeper.
The following video quickly outlines a potential creative student project for allowing students to fully process all they have learned from the video and enhancing that knowledge using the resource The Great Mystery from UCMP Berkeley, a great resource to use when teaching all things evolution.
The video begins with a quote by Walter Alverez:
"Understanding how we decipher a great historical event written in the book of rocks may be as interesting as the event itself."
I really like this quote and I find that it is worth having the students explain what they believe it to mean and share their thoughts now that they have a better understanding of how we came to the conclusion that an asteroid was the likely cause of this mass extinction. Most students agree that it is amazing that we are able to know anything from the years before any people existed.
As a prelude to a future unit on global climate change, I have students complete the following T-chart (I like T-charts, they are a quick and easy way to compare and/or organize information):
On the left side put the heading How The Asteroid Impact Altered the Ecosystem and on the right put the heading How Climate Change May Alter the Ecosystem. I give students about 10 minutes to complete this, using research if needed. I don't want to make this a large assignment as the main point is to provide them with a reference point to connect with when we begin that particular unit and to begin to wonder if we are not heading toward a similar fate as the dinosaurs.