© Jiuguang Wang
Do sea levels rise when ice melts? Does it matter whether the ice is on land or in the ocean? Students design an experiment to find out. They collect data, graph their results, and interpret their findings. Along the way, they learn about density, displacement, and climate change.
In this lesson, students will
- Plan, carry out, and interpret results of a scientific investigation.
- Explain why melting land ice causes sea levels to rise, but melting sea ice does not.
- Recognize the far-reaching effects of global climate change.
Teacher tip: This activity can be performed as a demonstration or in student groups.
This activity was selected for inclusion in the NSF/NOAA/DOE-funded Climate Literacy and Energy Awareness Network’s (CLEAN’s) collection of educational resources! CLEAN is a nationally recognized project in which climate scientists and educators rigorously review and select high-quality online resources to be part of a collection. It was also used by the National Parks Service to create a demonstration video.
- 2 identical clear food storage boxes (approximately 6 inches square) per group
- 8 sticks of classroom modeling clay per group
- 1 ruler per group
- 1 tray of ice cubes per group (may need to start storing ice cubes ahead of time)
- 1 liter of water per group
- Sea Level Rise Worksheets (1 per student)
- global climate change: change in average global temperature, rainfall, and wind patterns as a result of increased greenhouse gases in the atmosphere
- greenhouse gases: gases in Earth’s atmosphere that trap heat
- density: a measurement of compactness, measured as mass per unit volume
- displacement: the forced relocation of water due to a submerged or partially submerged object
- Have a discussion about global climate change and sea level rise. Ask students:
- Where is there a lot of ice in the world?
- Is the ice on land or on water?
- Will one or both cause sea level to rise when they melt?
- Tip: You can cover the explanation for why ice is less dense than water (and therefore floats) here, or you can wait until after the experiment.
- Guide students through the development of a question about the melting of ice and sea level rise. Which type of melting will cause an increase in sea level? Have each student record the question and a prediction on the worksheet.
- Tell the students that they will be working in groups to design an experiment to answer their question.
- Introduce the materials. Give as much or as little guidance about how to use the materials as is appropriate for your class.
- Tip: if appropriate for your class, discuss the importance of controlling variables that are not being tested.
- Have students discuss their ideas with their small groups. Afterwards, discuss each group’s ideas as a class. Make sure each group has a workable experimental design (see suggested procedure below). Have each student describe and/or draw their group’s experimental design in the “methods” section of the worksheet.
This procedure is only a suggestion - it’s okay if your students come up with something slightly different. Check to make sure they are investigating the correct question and control the variables they are not testing (i.e., each container should contain the same number of ice cubes, the same amount and arrangement of clay “land,” and should start with approximately equal water levels).
- Place half of the clay into one side of each box. Form the clay to represent land rising out of the ocean.
- Place about 6 ice cubes on the “land” in the first box. Place the same number of ice cubes next to the clay in the second box, so that they are resting on the bottom of the container.
- Pour water into the container where the ice is resting on the bottom until the ice is floating (NOT resting on the bottom).
- Pour water into the container with the ice resting on the clay until the water levels in the two containers are approximately equal.
- Have students measure and record initial measurements of water depth (in mm). They may wish to draw a line in the clay at the initial water level.
- Leave the setup. Students should measure the water depth every hour (or other regular interval) and record the results, until the ice is completely melted.
- Have each group graph their results on the board, on chart paper, or on butcher paper (see sample graph below) and display the graphs so everyone can see.
- Tip: You may wish to draw the axes ahead of time so the students can simply fill in their data. Younger students might find it easier to place Post-It notes on the board (1 Post-It per mm water depth) to form the bar graph, instead of drawing the graph. With older students, you may wish to make a line graph instead of a bar graph.
- Lead a discussion about the results, using the information in the “Background for Educators” section to help students understand their results.
- Have each student write a conclusion on their worksheet summarizing what happened and why.
Have another discussion about global climate change. Use the following questions to generate discussion:
- Why might we be concerned about sea level rise? (Coastal areas will be flooded. People will lose their homes. Some fresh water resources will become too salty to use. Habitat loss will occur.)
- What can we do to help slow this process by using less fossil fuel? (Take public transit instead of driving, eat local foods, turn off lights and electrical equipment when not in use, plant a tree, reduce, reuse and recycle.)
One consequence of climate change is the melting of ice caps, glaciers, and sea ice, including polar ice in Greenland and Antarctica. Substantial melt of these massive glaciers will cause a rise in sea level along coastlines throughout the globe (Climate Institute, n.d.). This activity explores how melting ice impacts sea level.
Water is an unusual liquid because it expands when it freezes. In general, liquids do not expand upon freezing, but rather contract and become denser as temperature drops. Like other liquids, as water begins to cool, it becomes more and more dense. But, because of the physical structure of the water molecule, it continues to become denser until just before freezing, when it expands. This expansion occurs at the point at which freezing begins (around 4°C). At this temperature water molecules arrange themselves into a crystal lattice structure that is significantly less dense than the liquid form. Because of this decrease in density at the point of freezing, ice always floats on water (US Geological Survey, 2014).
When objects are totally submerged in water, they displace an amount of water equal to their volume. However, because ice floats on water and is not completely submerged, ice does not displace an amount of water equal to its volume. Instead, it displaces less than its total volume of water. The water that floating ice displaces is equal to the volume that the ice would take up if it melted and became water again. In other words, floating ice displaces water equal to the mass of the ice. When ice melts, the mass of the ice is conserved, but the crystal lattice structure of ice disappears and the volume decreases and becomes equal to the volume of water it displaced in its ice form.
Therefore, when floating ice melts, the melted water is equal only to the volume of the ice that was submerged. This means that when floating ice melts, it contributes no additional volume to the body of water. We see this phenomenon when we let ice melt in a glass of water. The water does not overflow because the ice has already displaced water equal to the volume it will take up upon melting.
Ice already in the oceans does not contribute to sea level rise, but ice covering land will contribute to sea level rise upon melting. For a video on this topic featuring the same activity in this lesson plan, click here.
The effects of sea level rise are global. According to maps created by the Bay Conservation and Development Commission for the San Francisco Chronicle (Kay, 2007), a 1 meter rise in sea level would submerge “parts of Corte Madera, San Rafael, Hayward, Newark and much of the Silicon Valley shoreline.” In San Francisco, “Mission Bay housing and office developments, Caltrain tracks, Candlestick Point redevelopment, Heron's Head Park….parts of Treasure Island, and the San Francisco and Oakland airports” would all be under water.
- 1e. Students know matter has three forms: solid, liquid, and gas.
- 1f. Students know evaporation and melting are changes that occur when objects are heated.
- 1g. Students know that when two or more substances are combined, a new substance may be formed with properties that are different from those of the original materials.
Investigation and Experimentation
- 5c. Use numerical data in describing and comparing objects, events, and measurements.
- 5d. Predict the outcome of a simple investigation and compare the result with the prediction.
Investigation and Experimentation
- 6b. Students will develop a testable question.
- 6f. Students will select appropriate tools and make quantitative observations.
- 6g. Students will record data by using appropriate graphic representations, and make inferences based on those data.
- 6h. Students will draw conclusions from scientific evidence and indicate whether further information is needed to support a specific conclusion.
- 6i. Write a report of an investigation that includes conducting tests, collecting data or examining evidence, and drawing conclusions.
Physical Sciences: Density and Buoyancy
- 8a. Students know density is mass per unit volume.
- 8c. Students know the buoyant force on an object in a fluid is an upward force equal to the weight of the fluid the object has displaced.
Science & Engineering Practices
- Developing and Using Models: Develop and/or use models to describe and/or predict phenomena. (3-5; 6-8)
- Asking Questions and Defining Problems: Ask questions that can be investigated and predict reasonable outcomes based on patterns such as cause and effect relationships. (3-5)
- Planning and Carrying out Investigations: Plan and conduct and investigation collaboratively to produce data to serve as the basis for evidence. (3-5) Collect data to produce data to serve as the basis for evidence to answer scientific questions. (6-8)
- Analyzing and Interpreting Data: Represent data in table and/or various graphical displays to reveal patterns that indicate relationships (3-5; 6-8). Analyze and interpret data to make sense of phenomena, using logical reasoning, mathematics, and/or computation (3-5).
- Constructing Explanations and Designing Solutions:Use evidence to construct or support an explanation or design a solution to a problem. (3-5) Construct an explanation using models or representations. (6-8)
Disciplinary Core Ideas
- ESS3.C: Human Impacts on Earth Systems: Human activities in agriculture, industry, and everyday life have had major effects on land, vegetation, streams, oceans, air and even outer space. (Grade 5)
- PS1.A: Structure and Properties of Matter: The amount (weight) of matter is conserved when it changes form, even in transitions in which it seems to vanish (Grade 5). The changes of state that occur with variations in temperature or pressure can be described and predicted using these models of matter. (6-8)
- ESS3.D: Global Climate Change: Human activities such as the release of greenhouse gases from burning fossil fuels, are major factors in the current rise in Earth’s mean surface temperature (global warming) (6-8).
- Cause and Effect: Cause and effect relationships are routinely identified, tested, and used to explain change. (3-5; 6-8)
- Stability and Change: Change is measured in terms of differences over time and may occur at different rates; Some systems appear stable, but over long periods of time will eventually change (3-5). Explanation of stability and change in natural or designed systems can be constructed by examining the changes over time and forces at different scales (6-8).
Related Performance Expectations
- 5-PS1-2: Measure and graph quantities to provide evidence that regardless of the type of change that occurs when heating, cooling, or mixing substances, the total weight of matter is conserved.
- MS-PS1-5: Develop and use a model to describe how the total number of atoms does not change in a chemical reaction and thus mass is conserved.
- Climate Institute. (n.d.). Consequences of Climate Change on the Oceans. Retrieved November 17, 2014 from http://www.climate.org/topics/sea-level/
- Kay, Jane. (2007). Consequences of a rising bay/global warming: New set of maps reveals how melting polar ice could change shoreline and carry a high price for entire region. Retrieved November 17 2014, from http://www.sfgate.com/news/article/CONSEQUENCES-OF-A-RISING-BAY-GLOBAL-WARMING-2647936.php#photo-2127432
- National Park Service. Explaining Climate Change Videos. Retrieved November 10, 2014 from http://www.nps.gov/subjects/climatechange/explainingccvideos.htm.
- US Geological Survey. Water density. (2014). Retrieved November 17, 2014 from http://water.usgs.gov/edu/density.html