Polar Bears and PCs: Technology’s Unintended Consequences

How Does an iPod Affect a Polar Bear?

Photo courtesy of Amanda Graham (Yukon White Light) via Flickr.

When we talk about the problems of global climate change, we tend to focus on cars and coal-burning power plants as major contributors. Yet there are other significant players, including consumer electronics. The number of cell phones, MP3 players, laptops, and flat-screen TVs is increasing rapidly, and not just in wealthier nations. It is estimated that one in nine people in Africa has a cell phone – and those numbers are expected to continue growing.

A recent report from the International Energy Agency (IEA) estimates that new devices such as MP3 players, cell phones, and flat-screen TVs will triple energy consumption. Two hundred new nuclear power plants would be needed just to power all the TVs, iPods, PCs, and other devices expected to be used by 2030.

For example, consider televisions. The IEA estimates that 2 billion TVs will soon be in use across the world (an average of 1.3 TVs for every household with electricity). TVs are also getting bigger and being left on for longer periods of time. IEA predicts a 5 percent annual increase in energy consumption between 1990 and 2030 from televisions alone.

While consumer electronics is the fastest growing area, it is also the area with the least amount of policies to control energy efficiency. Total greenhouse gas emissions for electronic gadgets is currently at about 500 million tons of carbon dioxide per year. If nothing is done, the IEA estimates that the figure will double to about 1 billion tons of carbon dioxide per year by 2030. However, the agency says that existing technologies could reduce this figure by 30-50 percent at little cost. Allowing consumers to regulate energy consumption based on the features they actually use, minimum-performance standards, and easy-to-read energy labels can help consumers make smarter energy choices about their personal electronics.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

This story connects to two National Science Education Standards domains: Science and Technology and Science in Personal and Social Perspectives. The Science and Technology content standard states:

Technological solutions have intended benefits and unintended consequences. Some consequences can be predicted, others cannot.

The Science in Personal and Social Perspectives content standard includes resource use and depletion, human-induced and naturally occurring hazards, and science and technology in society.

Ask students to consider electronic gadgets – cell phones, digital cameras and video cameras, MP3 players, flat-screen TVs, laptops, and so forth. Have students brainstorm the benefits of these devices. Easier communication, access to data, entertainment, and mobility will probably come up. Then ask students to brainstorm “costs” or negative characteristics. Expense will certainly be mentioned, but will the energy cost?

If you have access to an electric power monitor such as a Kill-a-Watt, you can have students plug in different gadgets and compare power consumption. This simple activity can give rise to a number of inquiry-based investigations, such as: What’s the most energy-efficient MP3 player?; Do laptops and desktops consume the same amount of power?; Does screen size (on an MP3, cell phone, laptop, or TV) affect power consumption?; and so on.

Share some of the figures from the IEA report with students. Discuss the idea that making technology (cell phones, laptops and Internet access) available to more people is a good thing, but there are intended and unintended consequences. Greater access to technology enables widespread communication and promotes education, but also requires more energy – most of which comes from fossil fuels. Burning those fossil fuels releases more greenhouse gases into the atmosphere, accelerating climate change and causing Arctic sea ice decline. So all those iPods do impact polar bears after all.

Rather than leave students discouraged, present them with a challenge. Remind them of the many benefits of technology and acknowledge that electronic gadget use will continue to grow rapidly. How can science and technology address the unintended environmental consequences of these tools? Assign small groups of students a particular piece of technology and have them brainstorm ideas that would promote energy efficiency – either on the part of the consumer or the manufacturer, or both. Have groups present their solutions to the class and discuss them. What common solutions were raised? What can students and their families do now to use their electronic devices in a responsible manner?

Here are some related resources from the Middle School Portal 2: Energy Sources, The Power of Electricity,  What is Happening to Polar Bears? Real Data, Claims, and Evidence. The October 2008 issue of the free online magazine Beyond Penguins and Polar Bears included articles about natural resources, the NEED project, and energy efficiency activities for home and school.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Jessica Fries-Gaither and published June 1, 2009 in the Connecting News to the National Science Education Standards blog. The post was updated 4/23/12 by Jessica Fries-Gaither.

Why Did the Anasazi Abandon Mesa Verde

Many middle school curricula include attention to ancient American people and their cultures. This blog entry may be helpful in making connections to the nature of science and scientific enterprises as part of an integrated approach in studying the Anasazi or ancient Pueblos. The story titled “Vanished: A Pueblo Mystery,” published in the New York Times, April 8, 2008, enlightens readers regarding the science of archaeology.

Archaeologists rely on empirical evidence to reconstruct past events. However, this empirical evidence does not normally emanate from controlled laboratory experiments, conceived of and performed at the scientists’ will. Rather, archaeologists use evidence left by the activities of not only people that lived long ago but other organisms as well. They must be skilled observers.

The graphic accompanying the article shows where the Anasazi migrated from–what is now southwestern Colorado–and where they migrated to–what is now the Davis Ranch and Tucson, Arizona, area. There is also a slide show of images of dwellings among other relevant artifacts. For archaeologists interested in this part of the world and these people, the article states, “the most vexing and persistent question in Southwestern archaeology [is]: Why, in the late 13th century, did thousands of Anasazi abandon Kayenta, Mesa Verde and the other magnificent settlements of the Colorado Plateau and move south into Arizona and New Mexico?”

This is not the first time this question has been asked or that an answer has been proposed based on evidence. For example, drought has been documented during this time, providing a seemingly good explanation for the migration. However, evidence suggests many people were able to survive the drought. That fact casts doubt on drought as the only cause for the migration. Further, the area the Anasazi migrated to was actually drier than that which they migrated from.

An alternate hypothesis is based on the pollen record. “Measurements of the thickness of pollen layers, accumulating over decades on the bottom of lakes and bogs, suggest that growing seasons were becoming shorter.” Even this fact in combination with the relatively short drought does not convince many archaeologists these were the reasons for the migration. Why did the Anasazi never return, even when the drought ended? Evidence suggests they did not leave in a hurry, but planned their exit as if they intended to return.

Even more interesting hypotheses are presented regarding the role of religion in the migration. Donna Glowacki, an archaeologist at the University of Notre Dame, cites evidence that suggests the early culture of the group, prior to the migration, included a tradition where only a select, privileged few had access to the largest, most well-equipped dwellings. She asserts a change can be detected after the migration in the southern villages. There evidence indicates fewer of these select kivas are found, suggesting there was less reverence for a select few. The article indicates this change could be analogous to the Protestant reformation.

So who’s right? Well, no one knows for sure, but the Village Ecodynamics Project is set to bring together these various hypotheses to see if a coherent, though probably somewhat complex explanation, or theory, can be constructed. The researchers will use evidence of “rainfall, temperature, soil productivity, human metabolic needs and diet, gleaned from an analysis of trash heaps and human waste” to reconstruct events and come to conclusions.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

The article illustrates well the nature of science. Our understanding of the Anasazi migration is undergoing revision in light of new evidence and reinterpretation of existing evidence from new perspectives. It calls attention to the various scientists working on the same project, each contributing unique expertise and building new knowledge. The article conveys several possible hypotheses, all of which need to be thoroughly investigated to see if any can be discarded. It underscores that scientists don’t have definitive, pat answers, only best guesses based on reasonable interpretations of much evidence. Several kinds of, or sources of, evidence are identified giving readers an indication of the nature of archaeology in particular.

Ask students to describe archaeology. Affirm their responses and ask them to elaborate as much as they can. They should use terms like ancient, culture, science, observation, inference and reconstruct. Ask students what kind of knowledge or skills a good archaeologist needs. They should include knowledge of anatomy, plants, and history, and excellent observational skills. Archaeologists need to be global thinkers, able to see relationships among seemingly disparate observations. They should be good team players. If needed, ask leading questions such as: What other fields of science might be related to archaeology? They should include botany, zoology, and anthropology even if they don’t use those names for them.

Explicit connections to life science and earth science can be made, particularly to botany and climate. Ask students how knowledge of the growing season can be inferred from the pollen record. How can inferences regarding wet or dry years be obtained from tree rings?

Here are some additional resources related to the nature of science and fields of science: Science Sampler: Jumping to the Right Conclusions, Inferences, and Predictions;  Presenting a Logical and Reasonable Case Using Logical and Reasonable Arguments; Frequently Asked Questions: Questions about Paleontology.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Mary LeFever and published April 11, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 4/23/12 by Jessica Fries-Gaither.

We Are All Connected to the Oceans: A Lesson to Help Students Understand the Ways Humans Impact Marine Ecosystems

Students can look at a globe or map and readily see that water dominates our planet. However, do students know that over 70 percent of the earth’s surface is covered by water? Do they realize the importance of the oceans?

Currently, 80 percent of all people live within 60 miles of a seacoast. Yet many adolescents still do not think that the ocean waters impact their lives and vice versa. There are many reasons for this naive thinking. A common one is “I don’t eat seafood so I don’t use ocean resources.” Other reasons can be attributed to lack of a personal connection with the oceans. Some students have never visited oceans and swam in their warm waters.

As educators, one of our goals is to help students understand the importance of their everyday actions.  The National Science Education Standards state that students should have an understanding of human impact on the environment.

To help students identify how humans impact the marine environment, make a personal connection with the oceans, and raise awareness of marine environmental issues, teachers can use this week-long lesson.  This activity will help students think critically within the context of important marine issues.

National Science Education Standards

This lesson closely aligns with three of the Science Content Standards of the National Science Education Standards: 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

Engage students in learning about their personal connection with the ocean. Have students act as marine scientists for a week. On day 1, students should read an article/blog post or watch a video clip that discusses current news about the oceans. Students should read different articles and watch different videos. Students should then write a brief “news report” of their own. This report should summarize the article or video that they read or watched.

In their news report, students should alert their audience to daily activities, such as littering or not recycling, that may impact and contribute to changing marine environments.

Here are some ideas for articles and videos:

Explore

On day 2 as marine scientists, the students will explore their marine articles and videos in an “environmental summit. ” In small groups, they will share their news reports and discuss the daily activities that they came up with.

Students should then group the activities into categories (i.e., littering and driving separately/not carpooling could be in a category titled “increased pollution”).  Students should determine the relative significance of each activity. Students may wish to use a rating scale to explain the impact (i.e., a rating of 5 would mean the daily activity directly damages the ocean in a negative way and a rating of 1 would mean the activity could potentially harm marine environments). Students will then share their categories and rating scales with the class.  List the categories and activities on the board.

Note — you should see similarities within the groups.  Raise students’ awareness of this and facilitate a class discussion centered around humans impacting marine environments.

Explain

On days 3 and 4, students will work in small groups of two to three to create an action plan.  The goal of this action plan will be to raise awareness of marine environmental issues and to identify how humans impact the marine environment.

In this action plan, students should:

  • State and describe why an action plan is needed.
  • Support their claims with real data.
  • Identify five human actions that impact the marine environment.
  • Propose a possible solution and identify steps humans can take to reduce their negative impact on the marine environment.

Evaluate (Assess)

On day 5, students will submit their action plans to the summit leader (the teacher). Students will explain their findings to the class and share their proposed solutions. Students will compare and contrast the various solutions through class discussion. Then students will journal or reflect on their own personal impact and what they can do to lessen this impact.

Expand

Middle School Portal 2 (MSP2) provides many great resources focused on the oceans.  For background information, try Earth’s Oceans.  This guide discusses the oceans as a part of the earth system — the link between oceans and climate; tsunamis; life science concepts such as ocean ecosystems, food webs, and biodiversity; real data – both sources of and projects that use real data; and related careers. There is  a section on common misconceptions about the oceans and a section about the science standards that the guide connects to.

Even though you might not teach a unit called oceans, the oceans can be used as a context within other units, such as ecosystems, energy transfer, systems thinking, or methods in science.

Another useful resource developed by MSP2  is Ocean Systems.  This guide focuses on earth and physical science, including volcanic island formation and tsunamis; life science concepts, including ocean ecosystems, food webs, and biodiversity; science in personal and social perspectives, including pollution, endangered species and conservation; and related careers.

Students may wish to use visuals to raise awareness. Ecoartspace is an organization that focuses on addressing environmental issues through the visual arts. In addition to their action plans, students can create visual works of art that can be displayed throughout the school to raise awareness.  (You may want to work in collaboration with your school’s art program).

This lesson lends itself to discussing climate change.  These resources will help you have that discussion:

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Brittany Wall and published March 29, 2010 in the Connecting News to the National Science Education Standards blog. The post was updated 4/9/12 by Jessica Fries-Gaither.

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.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

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.

The Relationship Between Sea Surface Temperature and Hurricane Activity

Is your unit on climate and weather approaching? Here’s some research you can use to enrich students’ understanding of weather. It can help you make real-world connections from the textbook and classroom to the research scientists working to understand the science of hurricanes.

The news comes from ScienceDaily. The article, Increased Hurricane Activity Linked to Sea Surface Warming, explains how two variables, sea surface temperature and atmospheric wind field, were used to model the conditions under which hurricanes form. When they focused on temperature, the researchers found that a small increase in sea surface temperature, 0.5 degrees C, had a large impact on hurricane activity.

Mark Saunders, one of the researchers from University College London, emphasized,

Our analysis does not identify whether greenhouse gas-induced warming contributed to the increase in water temperature and thus to the increase in hurricane activity. However, it is important that climate models are able to reproduce the observed relationship between hurricane activity and sea surface temperature so that we can have confidence in their reliability to project how hurricane activity will respond to future climate change.

An impressive, aggregate satellite photo of several hurricanes in the Gulf of Mexico during 2005 accompanies the article. There are also links to several recent, related stories.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

This news article connects directly to the Earth and Space Sciencecontent standard for grades 5-8 of the National Science Education Standards, which includes this fundamental concept: “Global patterns of atmospheric movement influence local weather. Oceans have a major effect on climate, because water in the oceans holds a large amount of heat.” The reported research also connects to the Science as Inquiry content standard.

If your students already have a good understanding of the science of hurricanes, ask them what they think would be different about the world’s hurricanes if the sea surface temperature increased just a half degree C. How do they think one could investigate that question? What other variables need to be considered? What other existing evidence could be used to inform one’s hypotheses? Suggest that they might look at the history of hurricanes and the sea surface temperature conditions under which they formed. Why would such an investigation be potentially useful?

Then show them the brief article and ask, What do you think Saunder’s intention was when he said, “Our analysis does not identify whether greenhouse gas-induced warming contributed to the increase in water temperature and thus to the increase in hurricane activity?” Lead students to the related ideas of methods of science, which include making inferences supported by the evidence. This research did not investigate what might contribute to sea surface temperature increases, only the effects of sea surface temperature increases.

Here are some additional resources that are part of the Middle School Portal 2 collection to facilitate your instruction regarding weather and climate:

 The Powerful Punch of  a Hurricane; El Nino and His Sister La NinaTracking El Nino; Detecting El Nino in Sea Surface Temperature DataOceans, Climate and Weather; Earth’s Oceans, and Ocean Temperatures.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Mary LeFever and published February 7, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 3/27/12 by Jessica Fries-Gaither.