What is Happening to Polar Bears? Real Data, Claims, and Evidence

Looking for a way to incorporate real data into your science class? Or maybe you want to work on evidence-based claims and reasoning. Perhaps you need an engaging way to tackle the subject of climate change. This lesson uses polar bears and sea ice data to promote critical thinking within the context of an important current event.

Lesson Objectives

  1. Students will be able to visually represent data by creating meaningful graphs.
  2. Students will make claims based on graphical evidence and support those claims with evidence-based reasoning.

National Science Education Standards

This lesson closely aligns with three of the Science Content Standards of the National Science Education Standards (NSES): Science as Inquiry, Life Science, and Science in Personal and Social Perspectives.

Science as Inquiry: Abilities Necessary to do Scientific Inquiry (Grades 5-8)

  • Use appropriate tools and techniques to gather, analyze, and interpret data.
  • Develop descriptions, explanations, predictions, and models using evidence.
  • Think critically and logically to make the relationships between evidence and explanations.
  • Recognize and analyze alternative explanations and predictions.
  • Communicate scientific procedures and explanations.

Life Science: Populations and Ecosystems (Grades 5-8)

  • Lack of resources and other factors, such as predation and climate, limit the growth of populations in specific niches in the ecosystem.

Science in Personal and Social Perspectives: Natural Hazards (Grades 5-8)

  • Human activities also can induce hazards…Such activities can accelerate many natural changes.

Engage

Begin the lesson by showing footage of polar bears in Hudson Bay with wildlifeHD’s Polar Bear Cam. Conduct a brief class discussion to elicit prior knowledge about the bears. Next, share some facts about polar bears with students, such as:

  • So far this fall, tour operators and scientists have reported at least four and perhaps up to eight cases of mature males eating cubs and other bears in the population around Churchill, Manitoba. (From Hungry polar bears resorting to cannibalism, December 3, 2009)
  • There are increased bear-human interactions, increased numbers of bears on shore, and bears staying on shore for longer periods of time in the Canadian Arctic. (From Can You Bear It? Churchill a Polar Pioneer, November 18, 2009)
  • The IUCN Polar Bear Specialist Group has listed eight of 19 polar bear subpopulations as currently decreasing, three as stable, and one as increasing. For seven, data were insufficient to assign a trend. (From Polar Bear Status Report, July 6, 2009)

You may wish to share the facts orally, list them on the board or on a PowerPoint slide, or create mock headlines for students to read. Ask students to discuss the facts in small groups, and come up with explanations for the facts (or headlines). Conduct a class discussion to share students’ explanations, and record and post them in a central location.

Explore

Next, group students into teams of 4 or 5 for an Idea Circle about polar bears. In an idea circle, each student reads a nonfiction (informational) text of their own choosing on a particular subject (in this case, polar bears). As each student selects his own text, a variety of reading levels and formats are represented within each small group and within the class. Ideally, no two students read the same text. Idea circles are an excellent strategy for differentiated instruction and a wonderful opportunity to incorporate children’s literature into a middle school classroom.

For an idea circle on polar bears, we’ve suggested titles from the Beyond Penguins and Polar Bears virtual bookshelves, including:

  • Ice Bear: In the Steps of the Polar Bear. Nicola Davies. 2005.
  • Life Cycle of a Polar Bear. Rebecca Sjonger and Bobbie Kalman. 2006.
  • Baby Polar Bear. Aubrey Lang. 2008.
  • Why Don’t Polar Bears Have Stripes? Katherine Smith. 2004.
  • A Polar Bear Journey. Debbie S. Miller. 2005.
  • Polar Bears: Arctic Hunters. Norman Pearl. 2009.
  • Ice Bears. Brenda Z. Guiberson. 2008.
  • Polar Bear Alert! Debora Pearson. 2007.
  • Polar Bears. Amazing Animals Series. Gail Gibbons. 2009.
  • 101 Facts About Polar Bears. Julia Barnes. 2004.

Your librarian or media specialist will be able to recommend other nonfiction titles as well.

After students read their individual texts, they share what they’ve learned with their small group, completing a graphic organizer in the process. Next, conduct another whole-class discussion and record information on a large chart displayed in a central location. Ask students to revisit their explanations from the “Engage” phase, clarifying and revising as needed.

Explain

In this phase of the lesson, students will work with real data to better understand the role of sea ice loss in changing polar bear populations. The Windows to the Universe lesson Graphing Sea Ice Extent in the Arctic and Antarctic provides up-to-date sea ice data and clear procedures for the lesson. You may wish to deal only with the Arctic data if your focus is on polar bear populations.

Graphing Sea Ice Extent in the Arctic and Antarctic
Students graph sea ice extent (area) in both polar regions (Arctic and Antarctica) over a three-year period to learn about seasonal variations and over a 25-year period to learn about longer-term trends.

Once students have completed their graphs, they will analyze the data and make evidence-based claims that explain why polar bear populations are changing. You may wish to use a graphic organizer to scaffold students’ work with claims, evidence, and reasoning. You may also wish to model this process if students are unfamiliar or unpracticed with these concepts.

At this time, you may choose to conduct another whole-class discussion to share claims, evidence, and reasoning. Student graphs and claims/evidence/reasoning graphic organizers serve as assessment for this lesson (see “Assess,” below).

Assess (Evaluate)

Class discussion during the “Engage” phase of the lesson can serve as a source of formative assessment. Additionally, observation of student behavior during the lessons’ activities can be used as an assessment tool.

Formal (summative) assessment for this lesson includes evaluating student graphs and claims, evidence, and reasoning using rubrics. In addition, you may also choose to assess student understanding of polar bear characteristics and populations.

Expand

Extend this lesson by introducing global climate change and albedo. The following resources may be helpful as you plan extension activities.

Graphing Thermal Expansion of Water and Greenhouse Gases
Two activities have students create graphs of concentrations of greenhouse gases and observe the thermal expansion of water. You may choose to have students also plot global temperatures as well as greenhouse gas concentrations to help them see the correlation between the two.

The Shiniest Moon
This nonfiction article is written for use with students in grades 4 and up. Students learn about two of Saturn’s moons, albedo, the relationship between heat absorption and temperature, and how decreasing sea ice in the Arctic actually contributes to further melting. The article is offered in various formats and reading levels, and related activities are suggested.

Other Related Resources

Create a Graph
Students will learn how to create area, bar, pie, and line graphs. They are provided with information about what each type of graph shows and what it can be used for. Students are given an example of each type of graph, but they can create graphs using their own data in the interactive tool.

WWF-Canon Polar Bear Tracker
For the last 5 years or so, the WWF-Canon Polar Bear Tracker has followed polar bears in the Arctic. Their positions are beamed from collars on the bears’ necks, via satellite to scientists, and then to this website. It allows us to get regular updates about how the polar bears behave in their arctic environment and how they may be affected by climate change. The site also includes multimedia and a kid’s zone.

Dot Earth
Follow climate-related news (including the latest from the climate talks in Copenhagen) with this New York Times blog.

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This post was originally written by Jessica Fries-Gaither and published December 16, 2009 in the Connecting News to the National Science Education Standards blog. The post was updated 3/27/12 by Jessica Fries-Gaither.