Here are suggested ways to engage students with this video and with activities related to this topic.
- Beginning a lesson: Start by explaining how long scientists have been collecting instrumental climate records. Then create a core sample in front of the classroom, using sand, pebbles, ash, and other earthen materials. As you add layers, explain that this is how sediments are deposited on Earth's surface.
Next, show students an ice cube. Point out that the ice cube is white in places because it contains air bubbles. Explain that ice cores also contain air bubbles that can be sampled for atmospheric gases. Finally, explain that both sediment core samples and ice core samples are like a timeline—one that stretches back much further than any instrumental record.
- Viewing the video: Use the following suggestions to guide students' viewing of the video.
- Before: Briefly explain that cores from different parts of the world contain different particles because the plants and geological events of the regions differ. Ask students the following question: If you had an ice core from a polar region, what kinds of information about climate do you think might be included in the core?
- During: Have students jot down the kinds of chemicals that get trapped in tropical ice and what they reveal about climate.
- After: Ask students, What did you find most interesting or most surprising? Was there anything that you found confusing?
- Doing a small group activity: Divide the class into small groups. Give each group a card with the name of a material that may be found in ice cores (e.g., volcanic ash, pollen grains). Ask them to describe how the material came to be embedded in ice. Then ask them to make an inference about conditions on Earth at the time the material was deposited. For example, sedimentary ash suggests volcanic activity, which might have produced lower temperatures, depending on how thick the ash cloud was. Pollen grains reveal which types of plants were flowering at the time the grains were trapped. Based on what we know about the growing conditions of different plant species, we can make certain assumptions about the climate of the area in which those plants grew.
- Doing research projects—individual: Help students understand how sedimentary layers (and objects found within them) are commonly dated. Assign different methods to students, including relative dating and absolute dating. Select students to share their research—which should include an explanation of the technique as well as when it should be used—with the class.
For more media and information about the topics in these teaching tips, see these links:
To learn more about scientific dating methods, check out Radiometric Dating, Dating Lava Flows on Mauna Loa Volcano, Hawaiʻi, and The Dating Game: Radioactive Carbon.