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Leigh first studied mountain glaciers in Sweden and Norway as an undergraduate from Carleton College and moved on to study ice sheets as a graduate student. Now she works as a researcher at the National Science Foundation’s Center for the Remote Sensing of Ice Sheets (CReSIS) and serves on the faculty at the University of Kansas. She is currently focused on understanding changes in outlet glaciers in Greenland, particularly Helheim Glacier on Greenland’s east coast.

The great ice sheet on Greenland is being watched closely because it is home to some the fastest moving glaciers on Earth. Researchers from CReSIS are particularly interested in the behavior of four of Greenland’s glaciers that flow to the sea, called outlet glaciers: Jakobshavn (yah’-cub-shaw-vin), Kangerdlussuaq (kong-ger-loose’-wok), Helheim, and Petermann. These glaciers are located in distinct geographic locations on Greenland’s east, west and north sides and provide insights into how the ice sheet is responding to change. For the past two years, Leigh and her colleagues, Meredith Nettles, (Lamont – Doherty Earth Observatory) and Gordon Hamilton (University of Maine) have been measuring changes on Helheim and Kangerdlussuaq glaciers.

As outlet glaciers flow toward the sea, the terminus (lowest end) breaks off, or calves, and pieces of ice float away, becoming icebergs. While we can see such changes with our eyes, and our brains record the memories of what we saw, science depends on measurements. Just as is the case in medicine, technologies that assist and extend our senses are required to assess the nature and rates of change that are occurring.

Icebergs are interesting, but Leigh and other scientists are more interested in the dynamics of ice flow in general. They are trying to explain the interaction of the ice with the rock or water below, which will help them to explain why, when, where, and how the ice breaks away. Their goal is to predict how the glaciers will change over time and what that might mean for sea level rise. They’re trying to assess what controls iceberg production, and how it differs each year.

HOW DOES ONE STUDY GLACIERS?

Leigh and her team travel to Greenland three or four times a year between May and September to install and check equipment, download and process data from their instruments, and take physical measurements and photographs of the glaciers. They’re usually there for two weeks at a time, but sometimes they spend as little as ten days or as long as four weeks, often dependent on the weather. Some other research groups camp out on the glacier, but Leigh’s team has different kinds of equipment needs. They live in a hotel in Tasiilaq, a town some 60 miles from the glacier. Evenings are frequently spent preparing and double-checking their equipment and processing data.

The study sites are on the glacier surface, which is heavily broken (or crevassed), so Leigh’s team relies on helicopter pilots to get to the research sites and find a safe landing place nearby. The pilots are familiar with the area though and, without visible landmarks like trees or buildings, use the known coordinates to locate the sites. As they make their approach, the pilots identify a landing site that is flat enough for the team to work a substantial distance away from the whirling rotors.

There are usually one or two helicopters in town, which are used for doctor visits, transporting patients, and general deliveries for the local people as well as working with the research teams. Leigh’s team understands that it is part of a system and must be both prepared and flexible in scheduling flights.

INSTRUMENTS USED FOR RESEARCH

Each season, Leigh and the team install Global Positioning System (GPS) units on the glacier. The GPS unit moves along with the surface ice as it flows toward the sea. Glaciers become thinner as they flow, so each GPS unit provides information about both where it is located and its elevation above sea level. The team’s GPS units obtain positioning information from nine satellites to determine their precise location and elevation. The GPS units enable the researchers to learn the direction and rate of the glacier’s surface motion and its height above sea level.

Every other year, the team downloads data from the GPS units and changes the solar-powered battery packs. The team members have not yet lost a unit, but they have had several close calls. They’ve had to rescue a few that fell into crevasses; once a unit was crushed by moving ice. The units they are using now are less expensive and automatically transmit data with a radio link to a receiver mounted on a rock outcrop above the glacier. But the connection is not always good. As a result, there may still be some data loss, but not nearly as much as would occur if the team lost a unit completely!

Automated weather stations (AWS), maintained by the team’s colleagues from Denmark, are installed at specific locations to provide daily records of temperature, wind speed and direction, and relative humidity on the glacier. Cameras focused on the terminus of the glacier enable scientists to watch calving events and to record the times and amount of ice that breaks free. Cameras also allow scientists to track the direction and rates of movement of crevasses and patches of debris that are visible on the surface of the ice.

This spring and last year, Leigh helped to install instruments to record salinity and temperature measurements in the fjord where the glacier reaches the sea. This information can be used to describe changes in the water flow and will help to explain the role of water movement into the fjord. Tide gauges also help the scientists determine if glacial motion is linked to tidal activity. The tide gauges provide other evidence about when calving occurs because of the wave that is generated when ice falls into the water. The arrival of that wave actually gives better data for calving events than pictures from the cameras, which only take pictures every 5-10 minutes.

DOING FIELD WORK

In addition to the right instruments and measurements, it’s critically important to have a knowledgeable, competent, and experienced team in any field-based situation. Obviously, the team shares a common interest in glaciers and ice, along with actual field experience in Greenland. But the team has specialist roles, too. For example, Meredith usually handles more of the logistics and instrumentation, while Gordon and Leigh, who have mountaineering experience, work well together as a coordinated field team.

The success of any mission also depends on being outfitted with and trained to use the appropriate gear. There are some distinct differences in NSF provisions for training and outfitting Greenland and Antarctic teams. Antarctic researchers get their clothing and basic field gear from NSF when they prepare to enter and leave Antarctica from a deployment center, with NSF-supported transportation to and from a field station. NSF also supplies specific equipment, which is checked in and out as researchers deploy from and return to the station.

In contrast, researchers who travel to Greenland fly to the nearest town served by commercial airlines. From there, pre-arranged charters take them to and from the study sites. As a result, researchers who go to Greenland typically buy their own clothing and basic field gear, and the project manager ensures that the necessary equipment has been ordered and delivered. Field teams familiarize themselves with the equipment they will use while they are still at their home site. One of the highest priorities upon arrival in Greenland is to verify that the equipment has arrived and is in good working condition. Another priority is clothing made from lightweight and quick-drying fabrics that wick moisture away from the body.

Conditions on the glacier can be dangerous, and training in survival strategies is necessary. Leigh’s team has harnesses and ice axes but is not always “roped up” like climbers. In the long run, it is safer to be on the ice for a short period of time than to spend the time preparing the ropes.

DOING RESEARCH

Obviously, communication is critically important as the pilot and the team make the ongoing decisions of the day. Maybe they will fly directly to the glacier to download data and change the battery pack, or instead fly to a rock site on the side of the fjord to install cameras. If weather conditions aren’t good for either of those choices, they wait for days with better weather.

The team has well-rehearsed strategies so they can place or retrieve their equipment quickly. They practice being efficient. They know who’s going to do what job and how to do it quickly. With a handheld drill, Gordon will drill holes for the poles on which GPS units are mounted. Meredith turns the GPS units on, and Leigh unloads the poles and installs them.

The poles are at least two meters (6.5 feet) long so that the equipment is well anchored in the ice. When all goes well, the team can install equipment in seven minutes. Because the ice is treacherous, the pilots rarely turn off the helicopter rotors. Instead, the pilots wait while the team works. It is often extremely loud and windy when installing equipment at the study sites!

There have been a few occasions when the helicopter rotor was turned off. At those times, Leigh has heard the rumble of ice cracking beneath her. She said, “It’s amazing to hear all this noise, but not to see anything happening. The noise may be coming from deep in the crevasses or far away.”

LIFE NEAR THE GLACIER

Because Helheim Glacier is located on the Arctic Circle, it isn’t completely dark, more like dusk, early in the summer. Leigh and the team are becoming well known in Tasiilaq. When there’s down time and little to do, she plays soccer with kids in the area or prepares food for the team and their Greenland friends. Obviously, the local people depend on the sea for their food; but pasta, rice, and potatoes are also commonly available. Fresh vegetables are only brought in seasonally. There are times when an apple might cost $10. When Leigh tried to make chili a couple years ago, she was surprised to learn that there were no dried beans to be found. They’re just not a part of the traditional Inuit diet.

The limited number of flights, due to the weather and darkness, makes it necessary for the local people to plan ahead and to be creative when supplies run low. One year, the school was running low on paper in April, and knew it wouldn’t get more until June! Teachers rationed their remaining supply, and did a lot of work on blackboards.

Interestingly, the glacier has retreated so far up the valley that it is not visible from town. The local residents are no longer able to see the changes in the glacier firsthand.

WHAT IS KNOWN AND REMAINING QUESTIONS

One of the primary improvements in research technology is the ability to get data throughout the year, even when it’s bitterly cold and dark…and therefore treacherous for travel to the polar regions. Some data come from satellite coverage of the Arctic, but satellite data can be obtained only when the satellite passes overhead every 8-11 days. In addition, instruments onboard satellites require ground-truthing, where measurements from “on the ground” are used to verify that the data recorded by instruments onboard the satellites are accurate.

Unlike the instruments onboard satellites, the instruments Leigh and her team have placed on the ice can record data at scheduled intervals (minutes to hours to days apart). They also store their data in devices that are durable and easy to download or retrieve. Improvements to these devices provide a tremendous advantage to the research team.

Leigh’s team has learned a lot about the small-scale changes of Helheim Glacier in the past few years, but several questions remain. In particular, the team would like to know more about how ocean circulation affects glacier flow, and how far up-glacier changes (iceberg calving, for one) can propagate.

Answering these questions will significantly help to explain the glacier system and what causes it to change. Researchers really don’t know anything about what is under the ice at Helheim. Researchers at CReSIS are working to measure the bed topography (the surface of the land under the ice), but it’s also important to know what type of rock or sediment it is made of, and how much water is directly below the ice.

MODELING ICEBERGS

These lessons all call for the creation of “icebergs” by freezing water in rectangular containers or film canisters. We’ve also been told by teachers that water balloons are an inexpensive way to create model bergs. Just fill the balloons with water, tie and freeze, and then cut and peel away the balloon when you’re ready to use the models! By using a variety of container shapes and sizes, you can simulate the many types of icebergs.

Floating a Bergy Bit (Grades K-3)
Students create icebergs and observe that they float in salt water. An assessment activity is also available for download.

Floating Ice Volume (Grades 4-5)
Students will measure how much ice floats above and below water and calculate its volume. An assessment activity is also available for download.

Do-It-Yourself Iceberg Science (designed for Grades 6-8, modify for K-5)
In this inquiry-based lesson, students will experiment with their own film canister “icebergs” to explore the principles of floating icebergs and ice density. The focus on density and calculating volume is too advanced for most elementary students, but the overall experimental design and ideas for further investigation would be useful for most elementary classes.

Turn these lessons into inquiry-based activities! Ask students to plan an investigation to determine:

• If the shape or size of an iceberg affects whether it sinks or floats
• If the shape or size of an iceberg affects the percentage of ice above and below the surface of the water
• If icebergs float in both salt water and fresh water
• If the concentration of salt (salinity) affects whether icebergs float or sink
• If the concentration of salt (salinity) affects the percentage of ice above and below the surface of the water

BUOYANCY AND DENSITY

While these general lessons don’t specifically focus on icebergs, they do help students develop an understanding about sinking and floating by comparing various objects. Students in grades 3-5 use the familiar sinking and floating context to focus on the principles of experimental design. Teachers may wish to combine these activities with the iceberg lessons above to fully develop the concept with their students.

Sink or Float? (Grades K-2)
Students make and test predictions about sinking and floating and classify objects according to whether they sink or float. Teachers can incorporate ice cubes into this lesson to focus on icebergs.

Sink It (Grades 3-5)
Students develop an experiment to test whether objects sink or float. Teachers can incorporate ice cubes into this lesson to focus on icebergs.

INCORPORATING LITERACY AND OTHER CONTENT AREAS

Incorporating reading, writing, and other cross-curricular activities helps students develop important skills and extends their knowledge. For high-quality children’s literature about icebergs, please see Icebergs and Glaciers: Virtual Bookshelf.

Growing Floaters and Shrinking Sinkers (Grades K-5)
Informational text (written at K-1, 2-3, and 4-5 grade bands) explores the concept of floating ice. At each grade band, the text is available in three forms: a text-only pdf, a full-color illustrated book (pdf), and an electronic book with recorded audio (Flash).

What’s Happening to the Emperor Penguins? (Grades 3-5)
Students learn about the habitat and behavior of emperor penguins and consider how icebergs might impact their ability to find food.

Summing Up the Disaster (Grades 3-5)
Students research the Titanic sinking and write and publish a newspaper article.

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This article was written by Jessica Fries-Gaither. For more information, see the Contributors page. Email Jessica at beyondpenguins@msteacher.org.

Copyright August 2009 – The Ohio State University. This material is based upon work supported by the National Science Foundation under Grant No. 0733024. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. This work is licensed under an Attribution-ShareAlike 3.0 Unported Creative Commons license.

THE TIP OF THE ICEBERG

You have probably heard the statistic that approximately 90 percent of an iceberg is found under water. That’s an amazing statistic to consider given the massive size of some icebergs, but the very fact that ice floats is pretty remarkable.

To understand why ice floats, it is necessary to understand the concept of density. Density is calculated by dividing an object’s mass (amount of matter) by its volume (the space it occupies), or D=M/V. Density essentially describes how tightly packed a substance’s atoms are. Substances with a high density have tightly packed atoms, while the atoms in a low-density substance are more spread out. Density is a defining property of a substance, and it is constant no matter how much of the substance there is. For example, pure gold always has a density of 19.3 g/mL (grams per milliliter). Pure liquid water’s density is 1.0 g/mL, and a standard by which to compare other substances.

When water freezes, the water molecules spread out to align in a definite crystalline structure. You’ve observed this if you’ve ever noticed the bump on an ice cube or had a can of soda explode in the freezer. While most other substances contract, water expands as it becomes a solid.

Because water expands as it freezes, ice takes up more space (has a greater volume) than the liquid water does. But the amount of matter hasn’t changed – it is just spread out over a larger space. This means that the density of ice (0.92 g/mL) is less than that of liquid water (1.0 g/mL). And because ice’s density is lower than that of water, ice floats in water.

What about the density of salt water? Because of the dissolved sediments and minerals, sea water is slightly denser than pure water. Its density is approximately 1.03 g/mL. That means that ice (like icebergs) also floats in sea water. In fact, fresh water from melting icebergs will form a layer on top of the denser sea water.

Density also explains why most of an iceberg is found beneath the ocean’s surface. Because the densities of ice and sea water are so close in value, the ice floats “low” in the water. Remember that the density of ice is 0.92 g/mL, and the density of water is 1.0 g/mL (1.03 for salt water). This means that ice has nine-tenths, or 90 percent of water’s density – and so 90 percent of the iceberg is below the water’s surface. In contrast, a piece of wood with a density of 0.5 g/mL (half that of water) would float with half of its volume below the surface of the water. A cork with a density of 0.2 g/mL (20 percent that of water) would float with 20 percent of its volume below the surface, and so on.

Of course, there are some small variations that affect the exact percentage of the iceberg below water. Icebergs may contain sediments, dust, and other particles picked up by the glacier before calving. They also may have algae growth in and on their submerged surface. These icebergs are not a pure substance, and thus their density is no longer 0.92 g/mL. The temperature and salinity of the water in which an iceberg is located may also vary, meaning that the sea water’s density may not be exactly 1.03 g/L. While these variations are common, they do not change the densities much – and so 90 percent is a good estimate for the submerged part of an iceberg!

LIFE CYCLES AND ECOSYSTEMS?

Although they aren’t living, icebergs do have a life cycle. They begin as part of a glacier, building for tens of thousands of years and slowly moving toward the ocean. Once an iceberg calves, it typically lasts for three to six years – shorter if it floats into warmer water. Waves wear away at the iceberg and crash it into other icebergs or land. Thawing and melting create crevasses (cracks) that may lead to further calving. Some icebergs simply melt away, while others collapse more violently. Some icebergs never move into warmer waters and may last 50 years or more.

Icebergs may appear sterile and lifeless, but that’s not the case. Ice algae may grow in-between ice crystals or on the underside of a berg, playing an important role in primary production and in the marine ecosystems. Small fish avoid predators by hiding in ice holes, while invertebrates come to feed on nearby krill. Seabirds may nest on icebergs as well.

Extremely large icebergs, such as B-15 and the more recent C-19, can negatively impact marine ecosystems. Large bergs can reduce the amount of sunlight hitting the water, thus decreasing the production of the phytoplankton that forms the base of the marine food web. They also block the paths that penguins use to reach open water to find food.

Adelie penguins dive off an iceberg near Paulet Island, Antarctica. Photo courtesy of Nick Russill via Flickr. Licensed under a Creative Commons 2.0 license.

Icebergs near the coast of Antarctica scour, scrape, and gouge the seafloor. Increased calving as a result of shrinking winter sea ice will create more disturbances on the seabed, where the majority (80 percent) of all Antarctic life occurs. While some disturbances create space for a high diversity of organisms, scientists believe that an increase in iceberg action may actually decrease biodiversity.

DANGER!

The well-known story of the RMS Titanic, which illustrates the hazards of icebergs, led to the formation of the International Ice Patrol. The Ice Patrol (administered by the U.S. Coast Guard) keeps a close watch over the area off the coast of Newfoundland, known as Iceberg Alley because of the high number of icebergs found in the waters.

The Ice Patrol collects data from a variety of sources: aircraft flights, radar, and ice sightings from ships. It uses computer modeling and current information to predict the path of icebergs and warn ships via radio and the Internet. While these precautions have reduced the number of incidents with icebergs, the risk still remains.

The Antarctic Circumpolar Current tends to trap icebergs within the Southern Ocean, although some occasionally escape and enter shipping lanes in the southern Atlantic, Indian, and Pacific Oceans. Icebergs and sea ice do present a problem for research vessels and cruise ships within the Southern Ocean, however.

LINKS

Icebergs
This site provides basic information and interesting facts about icebergs, shapes, sizes, and colors, the journey of an Arctic iceberg, dangers, and possible uses. The site may be appropriate for upper elementary students as well as teachers.

How Icebergs Work
A six-part article providing an overview of iceberg basics, life cycle, statistics, ecology, and danger.

Quick Facts: Icebergs
This page from the National Snow and Ice Data Center provides basic information on icebergs as well as links to the International Ice Patrol, U.S. National Ice Center, and other useful resources.

Density of Ice
This page explains the concept of density, provides an explanation of why ice is less dense than water, and why ice floats.

Icebergs are Hotspots for Life
This blog post discusses the ecosystem found around and on the underside of icebergs.

NATIONAL SCIENCE EDUCATION STANDARDS: SCIENCE CONTENT STANDARDS

The entire National Science Education Standards document can be read online or downloaded for free from the National Academies Press web site. The following excerpt was taken from Chapter 6.

Teaching about icebergs can meet the Physical Science content standard for grades K-4 and 5-8:

K-4 Physical Science

Properties of Objects and Materials

• Materials can exist in different states – solid, liquid, and gas. Some common materials, such as water, can be changed from one state to another by heating or cooling.

5-8 Physical Science

Properties of Objects and Materials

• A substance has characteristic properties, such as density, a boiling point, and solubility, all of which are independent of the amount of the sample. A mixture of substances often can be separated into the original substances using one or more of the characteristic properties.

CAN YOU MELT A GLACIER WITH PRESSURE?

Background
This demonstration shows students one reason a glacier moves. A glacier is a large mass of ice that acts like a river, flowing downhill under the influence of gravity. As snow layers accumulate and gather weight, the pressure builds up on the bottom layer. This causes the bottom layer of ice to melt and it becomes soft and pliable. This warmer layer reduces the friction with the ground underneath and allows the glacier to move faster. The melting of the ice due to pressure and its refreezing is called regelation. The softer ice moves outward like thick honey. The snow layers continue to compress and add weight and pressure to the layers below, which causes continuing relegation, and therefore movement.

Materials

• A loaf pan of ice, 2 cm (2 inches) or more thick
• 2 bricks or weights
• Thin metal wire
• 2 boxes the same height, at least 50 cm (20 inches) above the floor
• 2 wood or metal boards, 30 cm (1 foot) long, to hold up the ice block between boxes
• 1 dishpan or cookie sheet to catch drips

Activity Time
30 minutes

Objectives
The student will discover that ice can melt due to pressure. The student will also be able to state one way a glacier is able to move.

Directions
1. Place the boxes about 30 cm (1 foot) apart and put the metal or wood boards on top of them like a bridge.

2. Leave an inch or so between the 2 pieces of the bridge.

3. Set the block of ice on the metal or wood boards.

4. Place a thin wire over the ice and between the two pieces of the bridge.

5. Tie a heavy weight to each end of the wire (the weights will be dangling on
either side of the ice block).

6. Place a drip pan under the ice.

7. Observe what happens to the wire and what happens to the ice. (This begins to happen
quickly, but takes 20-30 minutes before you are able to pick up the ice block without the wire.)

8. Ask students to touch the ice block where the wire has sliced through.

Discussion

• What happened to the wire? (The wire sank slowly through the ice.)
• What happened to the ice? (The ice under the weighted wire melted.)
• Why did the ice not break into 2 pieces? (The ice refreezes above the wire.)
• How does ice melt normally? (By a rise in temperature)
• How did ice melt at the wire? (By pressure)
• Where on the ice block does the ice become a liquid? (Where the wire cuts)
• If glaciers do not have a change in temperature, how do they melt at the bedrock? (From weight of the snow and ice above it. The weight applies pressure and produces heat to melt the ice.)

Assessment
Ask each student to write an exit ticket that states why glaciers melt when the temperature is below freezing.

Extension
Ask students to design another experiment using pressure to melt ice. Different wires and weights could change the results of this lesson.

NATIONAL SCIENCE EDUCATION STANDARDS: SCIENCE CONTENT STANDARDS

The entire National Science Education Standards document can be read online or downloaded for free from the National Academies Press web site. The content standards are found in Chapter 6.

Content Standards Grade K-4:

Standard B: Physical Science

• Properties and Changes of Properties of Matter
• Motions and Forces

Standard D: Earth and Science

• Properties of Earth Materials

Standard F: Science and Personal and Social Perspectives

• Changes in Environments

Content Standards Grade 5-8

Standard B: Physical Science

• Properties and Changes of Properties of Matter
• Motions and Forces
• Transfer of Energy

Standard E: Science and Technology

• Understandings about Science

Standard F: Science and Personal and Social Perspectives

• Populations, Resources and Environments

BLUE ICE CUBE MELT

Background
This experiment will demonstrate one way a glacier moves. Glaciers are slow-moving masses of ice that exist where more snow falls than melts. The layers and layers of snow that fall year after year are compressed to form ice. Glaciers act like rivers, flowing downhill under the influence of gravity. As they move, glaciers can widen and deepen valleys, and grind boulders into pebbles.

Glaciers cover about 10 percent of the earth’s land, mostly in Greenland and Antarctica. Here, glaciers can be as much as 2 miles thick and weigh millions of tons. This weight can cause the bottom layer of ice to melt and to become soft and pliable. This soft ice, called meltwater, reduces the friction between the bedrock and the ice, causing the glacier to move more easily.

Why do students use blue ice cubes? Blue ice occurs in the polar regions in old ice. The color comes from compressed ice where the air bubbles have all been squeezed out.

Materials

Per team of 2:
• 2 (same size) ice cubes made with blue food coloring
• 1 sheet of wax paper
• 2 rubber fingertip pads (found at office supply stores)
• 1 pencil

Activity Time
20 minutes

Objectives
Students will discover that you can melt ice by using pressure without raising the temperature. They will understand that glaciers can move even in freezing temperatures due to the weight of the layers of ice.

Introduction
Begin by writing the Know-Wonder-Learn chart on the board. Ask students what they know about ice and write that under Know. Now ask them what they wonder about ice and write that below Wonder. As a class, complete this chart with what they have learned at the end of the investigation. Before giving directions, show pictures of glaciers to the class.

Directions
1. Place 2 ice cubes several inches apart on the wax paper.

2. Put the rubber fingertip on your index finger.

3. Leave one ice cube alone, making it the “control” in the experiment.

4. Predict what will happen to the ice cubes.

5. Push down with your index finger on one of the ice cubes for about 5 minutes, or take turns pushing down.

6. Observe what happens to both ice cubes.

7. Use a pencil to draw around the outside of each ice cube’s melt pool on the wax paper.

8. Move the ice around on the wax paper and see if it moves easily.

Discussion

• Which ice cube melted faster?
• What happened to the ice cube that you pushed on?
• Why is there more water around the one that you pushed on?
• Where did the dent in the cube come from? (Your finger)
• What is another way to do this experiment?

Assessment
Ask each student to write or draw an exit ticket that explains why glaciers melt when the temperature is below freezing.

Extension
Make this an inquiry-based lesson by asking students to try this same investigation and choose different surfaces (sandpaper, wood, concrete) when applying pressure. Students can also devise another method of pressure to melt ice cubes.

NATIONAL SCIENCE EDUCATION STANDARDS: SCIENCE CONTENT STANDARDS

The entire National Science Education Standards document can be read online or downloaded for free from the National Academies Press web site. The content standards are found in Chapter 6.

Content Standards Grade K-4

Standard B: Physical Science

• Properties and Changes of Properties of Matter
• Motions and Forces

Content Standards Grade 5-8

Standard A: Science as Inquiry

• Abilities Necessary to Do Science Inquiry
• Understandings about Science Inquiry

Standard B: Physical Science

• Properties and Changes of Properties of Matter
• Motions and Forces
• Transfer of Energy

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Reference

National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academy Press.

Ice Ice Baby Lesson Plans
18 ice-related lesson plans are available as downloadable pdf documents from CReSIS’s education page. Blue Ice Cube Melt and Can You Melt a Glacier, the two lessons described in this article, are included.

Ice Sculptures

In the Kalahari Desert of South Africa are some odd-looking rocks. The rocks are flat and polished, as if something very large and heavy has scraped across their surface.

Halfway across the world, in the southwest corner of Lake Erie, is Kelleys Island. The bedrock there is grooved. It looks as if something large and heavy has moved across the rock, gouging out these deep lines.

What caused these strange things? The flat, polished rocks of South Africa and the grooved rocks of Kelleys Island were left behind by giant moving walls of ice called glaciers.

Glaciers are made of ice. Ice is a solid. But glaciers are so large and heavy that they actually move like a liquid. You can think of glaciers as slow-moving rivers of ice.

Today glaciers can be found on very high mountains. Snow falling on high mountain slopes doesn’t melt. Instead the snow turns to ice and adds its own weight to the weight of ice already there. When the ice is heavy enough, the glacier begins to move down the mountain, spreading into the foothills and valleys below. As it moves, the glacier scrapes and shapes the mountain’s sides.

Like mountaintops, polar regions stay cold all year long. Glaciers grow there too. They press and grind the land below as they move. When a glacier reaches a coastline, pieces of ice can break off and form icebergs.

Today glaciers are found in only the world’s coldest places. But during ice ages, glaciers and ice sheets covered the land over much of Earth. Three hundred million years ago, the Kalahari Desert was covered by glaciers. That ice slowly moved. It scraped across the rock, leaving the flat, smooth rocks behind.

Starting around three million years ago, an ice sheet covered much of the midwestern United States. This ice sheet advanced and retreated many times. It retreated for the last time around fourteen thousand years ago. This ice sheet is responsible for the glacial grooves of Kelleys Island. As the glacier moved, it picked up heavy boulders and pushed them along. These boulders, some made of hard rock, scraped at the softer limestone of Kelleys Island, forming long channels. These channels are the glacial grooves of today. They are clear evidence of the wall of ice that once moved across the land.

Ice has shaped the world in surprising ways. The rugged coastline of Norway was once covered in ice. Today, fjords line the coast. Fjords are fingers of water that stretch inland along u-shaped valleys. Moving ice carved those valleys. The mountains of Europe and the Great Lakes of North America were also sculpted by ice. Glaciers formed giant lakes where none had been before and produced rich soil for growing crops. Even though the glaciers have retreated, we can see their sculptures all around us.

Glossary

fjord – a deep valley filled with water

glacier – a large mass of ice that slowly moves

ice ages – times in Earth’s history when the world was extremely cold

icebergs – large pieces of ice that float in the sea

ice sheet – a mass of ice that covers more than 19,000 square miles of land

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Flesch-Kincaid Reading Level = 5.1

Modified versions of this text are available for grades K-1 (Flesch-Kincaid Reading Level = 1.6) and grades 2-3 (Flesch-Kincaid Reading Level = 3.8). See below for links to all three versions in text, book, and electronic book forms.

GLACIAL FORMATION

How Do Snowflakes Become Ice? (Grades K-5)
Students model the formation of ice with marshmallows or, if it is available, snow. Lesson extensions suggest using snow cones or shaved ice to model the difference between snow, firn (an intermediate stage between snow and ice), and glacial ice. This lesson meets the National Science Education Standards: Science as Inquiry Content Standard, the Physical Science Content Standard, the Earth and Space Science Content Standard, and the History and Nature of Science Content Standard.

Glacial Pressure (Grades 3-5)
In this lesson plan, students model glacial formation through the compression of marshmallows, which represent snow. Students observe the effect of pressure exerted on marshmallows and draw conclusions about pressure exerted on snow.

This lesson meets the National Science Education Standards: Science as Inquiry Content Standard and the Earth and Space Science Content Standard.

GLACIAL MOVEMENT

Blue Ice Cube Melt (Grades K-5)
Students experiment with blue-colored ice cubes and learn that ice can melt under pressure. This lesson meets the National Science Education Standards: Science as Inquiry Content Standard, the Physical Science Content Standard, the Earth and Space Science Content Standard, and the History and Nature of Science Content Standard.

Modeling Glacier Dynamics with Flubber (Grades 2-3)
Modeling Glacier Dynamics with Flubber (Grades 3-5)

These hands-on activities simulate glacial flow. The students use a glacier-modeling compound made from glue, water, and detergent (“flubber”) to predict and observe glacial flow. The students discuss with the teacher how scientists determine glacial flow with real glaciers. The link opens a zipped file that contains three documents: the teacher’s guide, notes, and a worksheet.

This unit meets the National Science Education Standards: Science as Inquiry Content Standard and the Earth and Space Science Content Standard.

GLACIAL EROSION

Explaining Glaciers, Accurately (Grades 3-5)
This article from the National Science Teachers Association journal Science and Children describes two activities that help students develop correct understanding of how glaciers change the earth’s surface by plucking and abrasion. Free for NSTA members and nonmembers.

This lesson meets the National Science Education Standards: Earth and Space Science Content Standard.

INTEGRATING LITERACY

Use the books in this month’s Virtual Bookshelf and our Feature Story to help your students practice making predictions while reading!

It Doesn’t Have to End That Way: Using Prediction Strategies with Literature (Grades K-2)
Primary students listen to the beginning of a story, and then use details in the text and prior knowledge to predict the way the story will end.

This lesson meets the following NCTE/IRA standards: 3, 4, 11, 12.

Using Prediction as a Prereading Strategy (Grades 3-5)
This three part lesson includes teacher modeling, guided practice, and independent practice with response journals. The lesson uses fiction trade books, but the approach can be used with any text or content area.

This activity meets the following NCTE/IRA standards: 3, 5.

GRADES K-2 UNIT OUTLINE

Summary of Purpose for the Unit
This unit is designed to provide primary students with opportunities to learn about icebergs. Students observe ice and make and test predictions about whether icebergs of various sizes and shapes will be able to float. This helps build important science process skills and develop an informal understanding of physical science concepts such as buoyancy and density.

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Standards Alignment

National Science Education Standards: Science Content Standards

Science content standards are found in Chapter 6 of the National Science Education Standards.

Science as Inquiry (Grades K-4)

• Ask questions about objects, organisms, and events in the environment
• Communicate investigations and explanations

Physical Science (Grades K-4)

• Properties of objects and materials

Earth and Space Science (Grades K-4)

• Properties of Earth materials

IRA/NCTE Standards for the English Language Arts

View the standards at http://www.ncte.org/standards.

1 - Students read a wide range of print and nonprint texts.

3 - Students apply a wide range of strategies to comprehend, interpret, evaluate, and appreciate texts.

4 - Students adjust their use of spoken, written, and visual language (e.g., conventions, style, vocabulary) to communicate effectively with a variety of audiences and for different purposes.

5 - Students employ a wide range of strategies as they write and use different writing process elements appropriately to communicate with different audiences for a variety of purposes.

11 - Students participate as knowledgeable, reflective, creative, and critical members of a variety of literacy communities.

12 - Students use spoken, written, and visual language to accomplish their own purposes.

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Unit Outline

Engage
Read Lulie the Iceberg by Takamado no Miya Hisako (from our Water, Ice, and Snow virtual bookshelf) and ask students to share what they know about icebergs. Record student ideas on chart paper, or begin a class KWL chart (or one of the variations described in this article). If you’d like some background information before you begin the unit, please see the article All about Icebergs.

Explore
First, allow students to observe and experience ice using as many senses as possible – sight, smell and touch. Provide time for students to share their observations with one another. Next, present students with “icebergs” in a variety of sizes and shapes. Icebergs can be created by freezing water in film canisters as described in the lesson Do-It-Yourself Iceberg Science, or by filling and freezing water balloons and other containers of various shapes and sizes. Ask students to predict whether or not each iceberg will float when placed in water. Prompt students to justify their predictions. Record student ideas on chart paper, or have older students record their predictions in their science notebooks.

To test student predictions, place each “iceberg” in water and observe its behavior. We recommend using a large aquarium or other transparent container so students can gather around and observe from the sides of the container as well as from the top. Ask students to record their observations and draw pictures showing the position of the icebergs in the water. Were their predictions correct? Why or why not? Older students using science notebooks can write claims and conclusions at this time. If you started a KWL chart, provide time for students to revisit and revise their questions, and add new information to the “L” column.

Explain
Read Floating Ice (look for the Grades K-1 and 2-3 versions by scrolling down through the article) with students – either as an illustrated book or an electronic book. Discuss the text with students, linking it with student observations from the Explore phase. Again, allow students to revise the KWL chart used in the previous two phases.

Next, invite students to draw a picture of an iceberg in the ocean. Underneath their pictures, students should write (or dictate) what they learned about icebergs from the investigations and the text. Allow time for students to share their pictures and writing with one another. Teachers might also compile student work into a class book.

Expand
Ideally, student questions and interests drive this phase of instruction. One possibility is to compare the behavior of icebergs in freshwater and saltwater. Another is to learn about glaciers – massive sheets of ice from which icebergs calve. Finally, this iceberg investigation could be part of a unit about the states of matter or floating and sinking. See the article Using Icebergs to Teach Buoyancy and Density for more suggestions.

Assess
This unit provides opportunities for both formative and summative assessment.

Formative Assessment

• Observation of students’ participation in class activities throughout the unit will provide insight into their current understanding and engagement with the topic.
• Ongoing completion of the KWL chart or science notebook entries will allow teachers to modify the unit accordingly.

Summative Assessment
Student drawings and written/dictated facts serve as the source of summative assessment and indicates student understanding of icebergs. Such work is best assessed on a teacher-created rubric.

GRADES 3-5 UNIT OUTLINE

Summary of Purpose for the Unit
This unit is designed to provide elementary students with opportunities to model and investigate glaciers. It uses hands-on experiences and children’s literature to answer the questions How are glaciers formed?, How do glaciers move?, and How do glaciers shape the land?

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Standards Alignment

National Science Education Standards: Science Content Standards

Science content standards are found in Chapter 6 of the National Science Education Standards.

Science as Inquiry (Grades K-4 and 5-8)

• Ask questions about objects, organisms, and events in the environment
• Communicate investigations and explanations

Earth and Space Science

• Changes in the Earth and Sky (Grades K-4)
• Structure of the Earth system (Grades 5-8)

IRA/NCTE Standards for the English Language Arts

View the standards at http://www.ncte.org/standards.

1 - Students read a wide range of print and nonprint texts.

3 - Students apply a wide range of strategies to comprehend, interpret, evaluate, and appreciate texts.

4 - Students adjust their use of spoken, written, and visual language (e.g., conventions, style, vocabulary) to communicate effectively with a variety of audiences and for different purposes.

5 - Students employ a wide range of strategies as they write and use different writing process elements appropriately to communicate with different audiences for a variety of purposes.

11 - Students participate as knowledgeable, reflective, creative, and critical members of a variety of literacy communities.

12 - Students use spoken, written, and visual language to accomplish their own purposes.

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Unit Outline

Engage
Tell students that they are going to be learning about glaciers. Invite students to picture walk or skim through various books about glaciers, including the titles in our virtual bookshelf. Next, ask students to complete a KWL chart (or one of the variations described in this article) independently, in small groups, or as a class. If you’d like to learn more about glaciers before beginning the unit, the article Glaciers: Earth’s Rivers of Ice may be helpful.

Explore
First, students should have a chance to investigate how glaciers form. The lessons How Do Snowflakes Become Ice? and Glacial Pressure model the formation of compacted ice with marshmallows, snow cone ice, or snow (if available). Students should draw diagrams, record their observations, and write about the process of glacial formation. Science notebooks can be used for this purpose. Students should also update their KWL charts by adding new information to the “L” column and any new questions that may have arisen.

Next, students should have a chance to investigate how glaciers move. Several lessons can be used to accomplish this purpose. In Blue Ice Cube Melt and Can You Melt a Glacier with Pressure? (both described in the article Ice, Ice, Baby), students learn that ice can melt through pressure – an important concept in understanding glacial movement. Modeling Glacier Dynamics with Flubber (versions for grades 2-3 and 4-5) allows students to simulate the movement of a glacier and learn that all parts of a glacier don’t always move at the same speed. Again, have students record observations, draw diagrams, and write about what they’ve learned. They should also update their KWL charts with new information and questions.

Finally, students should have a chance to investigate how glaciers erode and shape the land. In the lesson How Does Ice Break Down Mountains?, students observe how freezing water affects various objects (including rocks). The article Explaining Glaciers, Accurately describes two activities that help students develop correct understanding of how glaciers change Earth’s surface by plucking and abrasion. Again, have students record observations, draw diagrams, and write about what they’ve learned. They should also update their KWL charts with new information and questions.

Explain
During this phase, students deepen the understanding they gained during the Explore phase by reading and discussing children’s literature, including the books about glaciers from our virtual bookshelf. Students can also read our Feature Story Ice Sculptures, which describes the effects glaciers have had on landscapes around the world. Students can practice the reading comprehension strategy of visualizing with a template. For more information, see Visualizing to Understand Content Area Text. If you wish to have students practice note taking, the Note It 3 Ways template might be helpful. If students are reading and discussing in small groups, our idea circle graphic organizer might be used instead.

Students will then use what they’ve learned in the investigations and from children’s literature to create Question and Answer Books. Each page of the book includes a question and then a paragraph and an illustration that provide the answer. While students should use questions and facts from their KWL charts to construct their books, most will answer these three questions (at a minimum): How are glaciers formed?, How do glaciers move?, and How do glaciers shape the land?

Expand
This unit can lead into a study of other forces that shape the Earth’s surface – wind, water, volcanoes, and earthquakes. Our issue Earth’s Changing Surface contains a wealth of resources for teaching about these topics.

Assess
This unit provides opportunities for formative and summative assessment.

Formative Assessment
Formative assessment is conducted throughout the unit. For example:

• Observation of students’ participation in class activities throughout the unit will provide insight into their current understanding and engagement with the topic.
• Student observations, diagrams, writing, and completion of the KWL chart will provide an ongoing look at their current level of understanding.
• Observation of students taking notes or visualizing content area text during the Explain phase will provide insight into their understanding of the material being read as well as their ability to take notes from text. Provide support for students as needed.

Summative Assessment
Question and answer books serve as the source of summative assessment. Books can be assessed on a teacher-created rubric.

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This article was written by Jessica Fries-Gaither. For more information, see the Contributors page. Email Jessica at beyondpenguins@msteacher.org.

Copyright August 2009 – The Ohio State University. This material is based upon work supported by the National Science Foundation under Grant No. 0733024. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. This work is licensed under an Attribution-ShareAlike 3.0 Unported Creative Commons license.