Lab 2: Earth's Frozen Oceans
The lab activity described here was developed by Erin Bardar of TERC for the EarthLabs project.Use the button at the right to navigate to the student activity pages for this lab. To open the student pages in a new tab or window, right-click (control-click on a Mac) the "Open the Student Activity" button and choose "Open Link in New Window" or "Open Link in New Tab."
Investigation Summary and Learning Objectives
In Part A, you will learn about how sea ice forms and influences ocean currents around the globe. In Part B of the investigation, you will look at how sea ice thickness changes over time. Finally, in Part C, you will use NSIDC sea ice index data to explore changes in sea ice extent on multiple time scales including months, years, and decades.
After completing this investigation, students will be able to:
- describe the relationship between sea ice and ocean currents;
- describe how sea ice thickness and extent change over time;
- describe the timescales associated with sea ice growth and melt; and
- explain why changes in sea ice over time are important.
Activity Overview and Teaching Materials
In Part A:, students are introduced to sea ice and how it is connected to ocean circulation. They begin by watching the BBC/Discovery Channel video Frozen Planet: Icy Finger of Death from the popular television series Frozen Planet. They then conduct an experiment to explore how salinity affects the density of ocean water and how the formation and melt of sea ice influences ocean currents all around the globe. For each small group of students, you will need:
- 3 small, clear containers (e.g., 250 mL beakers)
- masking tape
- fresh (tap) water
- salt water (35 g/L salinity)
- food coloring
After completing the experiment, students use an online interactive to explore thermohaline circulation in more detail. (NOTE: This interactive will require student computers to have an up-to-date version of Flash.) Next, students watch a brief, narrated NASA video showing the thermohaline circulation system in three dimensions. (NOTE: This video may require Real Player to be installed on student computers.)
Time estimate: 50-75 minutes
In Part B: Students examine a plot of sea ice thickness over the course of a year to help them understand the role of heat transfer between the cryosphere and atmosphere. They then consider the dynamic forces that influence sea ice thickness and watch a short YouTube video showing the vertical undulating motion of sea ice. Next, students interpret images showing how sea ice age (thickness) has changed in recent years and learn about the Arctic Oscillation, a large-scale seesawing weather pattern that affects sea ice extent and thickness. Interested students can use the Measuring Sea Ice Thickness Power Point presentation under How Do We Know What We Know?, as a launching pad for further investigation of some of the tools and techniques scientists use to measure sea ice thickness.
Time estimate: 50-60 minutes
In Part C: Students focus on sea ice extent, looking at how sea ice extent varies on seasonal and annual time scales. They will create an animation of Arctic sea ice extent changes over the course of one year and then five years using the National Snow and Ice Data Center's Sea Ice Animation Tool. They will then use Microsoft Excel or another spreadsheet program (if available) to plot monthly sea ice extent for one year. Part C ends with a wrap-up discussion about what students have learned about sea ice formation, extent, thickness, and changes over time.
Time estimate: 50-100 minutes
- Stop and Think Questions (PDF (Acrobat (PDF) 427kB Jan3 13) and Word (Microsoft Word 281kB Jan3 13))
- Suggested Answers (Microsoft Word 548kB Jan3 13) to Stop and Think Questions
Teaching Notes and Tips
In Part A: If time or supplies are limited, the density/circulation experiment can be done as a front-of-the class demonstration.
In Part B: If YouTube is blocked on your school computers, consider one of the following options:
- Have students watch the video on a mobile device such as a smart phone or tablet that runs on a 3G/4G connection rather than the school's internet or wireless connection.
- Have students watch the video on a home computer where YouTube is not blocked.
- Use a converter site such as Convert.Files to download the YouTube video to a personal computer, CD, or memory stick outside of school and project the video for students to watch as a class.
In Part C: To save time, you might consider assigning a different year to different small groups of students rather than have all groups collect and graph data for all 5 years.
Purpose of the discussion: In this lab, students were introduced to Arctic sea ice, which helps regulate ocean circulation and global climate. Use this discussion opportunity to make sure students understand the role of sea ice and why it is important for scientists to monitor and understand how it changes over time.
Facilitation Tips: Write the primary discussion question on the board and give students three minutes to share ideas in pairs or to write in their notebooks before starting the full class discussion.
Primary discussion question: Why is it important to understand how sea ice changes over time?
- What causes sea ice thickness and extent to change over time?
- What types of changes do scientists expect to see in sea ice over a year? over 5 years or more?
Wrap Up: Even though sea ice is found primarily in the polar regions, it influences the whole world. Changes in the amount of sea ice can disrupt normal ocean circulation, which directly impacts global climate. Sea ice is also highly reflective and plays a large role in keeping the planet cool. As they continue through the cryosphere unit, students will learn more about the importance of sea ice as a climate indicator.
- Have students write down the learning objectives for Lab 2.
- Have students record answers to all Stop and Think questions.
- Have students record answers to all Discussion questions.
- In Part A: Have students take notes and record reactions as they watch the Icy Finger of Death and global conveyor belt videos.
- Have students write down any questions they still have about the content covered in this lab.
There are several options for assessment of student understanding of material introduced in this lab. Choose from the following list, or create your own assessments.
- Assess student understanding of topics addressed in this investigation by grading their written responses to the Stop and Think questions or by using Stop and Think questions as part of whole-class or small group discussions.
- Written Test for Lab 2 (Microsoft Word 2007 (.docx) 245kB Jan11 13). Answer key (Microsoft Word 2007 (.docx) 445kB Jan11 13)
National Science Teaching Standards
Lab 2 supports the following Next Generation Science Standards (NGSS):
Science and Engineering Practices
4. Analyzing and interpreting data
7. Engaging in argument from evidence
Disciplinary Core Ideas
ESS2.A: Earth's Materials and Systems
ESS2.D: Weather and Climate
2. Cause and effect; mechanism and explanation
4. Systems and system models
5. Energy and matter; cycles, flows, conservation
7. Stability and change
- For additional background information about the processes involved with the growth and melt sea ice, read the NSIDC sea ice primer Processes: Thermodynamics.
- Read through this NOAA tutorial on the Global Conveyor Belt to familiarize yourself with how the formation of sea ice influences global ocean circulation.
- For additional background information about sea ice dynamics, read the NSIDC sea ice primer Processes: Dynamics.
- To learn more about Arctic sea ice trends, read the NASA Earth Observatory Feature Article Dwindling Arctic Ice.
- If time and circumstances allow, consider having students make their own sea ice.
- The Earth Exploration Toolbook Chapter Whither Arctic Sea Ice? walks users through techniques for analyzing sea ice extent data with image processing and spreadsheet software.
The Earth Exploration Toolbook is a collection of computer-based Earth science activities. Each activity, or chapter, introduces one or more data sets and an analysis tool that enables users to explore some aspect of the Earth system.
Step-by-step instructions in each chapter walk users through an example-a case study in which they access data and use analysis tools to explore issues or concepts in Earth system science. In the course of completing a chapter, users produce and analyze maps, graphs, images, or other data products. The ultimate goal of each activity is to build user's skills and confidence so they can use data to conduct their own investigations of the Earth system.