Hands-on Activity Unraveling Rising Sea Levels:
Exploring Density Through Mixtures and Solutions

Learning Objectives

After this activity, students should be able to:

• Understand density and how it affects the behavior of different substances in water.
• Simulate real-world phenomena by exploring how the addition of freshwater impacts ocean density and contributes to rising sea levels.
• Apply the engineering design process by planning, creating, testing, and refining mixtures.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards - Science

Common Core State Standards - Math

Materials List

Each group will need:

• 1 beaker
• 1 graduated cylinder
• 25 mL of water and salt solution
• 1 stir stick
• Exploring Density Through Mixtures and Solutions Worksheet (1 per student)

For the entire class to share:

• access to a short online Google Earth video
• paper clips (all groups should use paper clips of the same size and same material)
• measuring cups
• measuring spoons
• 1 lb sugar
• 26 oz salt
• 48 oz vegetable oil
• 16 oz corn syrup
• 14 oz baby oil
• 16 oz liquid starch
• 17 oz olive oil
• 16 oz vinegar

Worksheets and Attachments

Pre-Req Knowledge

Students should have:

• Knowledge of what constitutes a mixture and a solution.
• A basic understanding of density.
• Knowledge of basic laboratory safety rules and procedures.

Introduction/Motivation

Today, we are going to begin with a two-minute muted Google Earth time-lapse video. (The video shows melting ice caps over the past 40 years.) Let’s watch closely and see what we can observe. (Play the video: Melting Ice Time Lapse Video [2:05]).

Now that we’ve watched the video, I want you to take a moment to brainstorm on what you think is happening. Think about what questions you may have. Think about it silently for a minute. (Pause for brainstorming). Turn to your elbow partner and share your thoughts. Discuss what you believe is happening in the video. Let us hear some of your ideas or questions you may have. Who would like to share what you and your partner discussed? (Students share their ideas. Record responses on the board. Answers could include melting ice caps, melting glaciers, or global warming.)  These are great observations. Now, let me pose a question: What effects, if any, do melting ice caps entering our oceans have? Think about how this might affect our environment and the world.

Today, we will step into the role of ocean engineers to create the densest mixture or solution. We will take part in an experiment that will help us understand the concept of density and how different substances interact with water. You will have the opportunity to use salt, sugar, vegetable oil, olive oil, and vinegar to concoct your mixtures. Once prepared, we will test your creations by adding them to water, which will simulate the ocean. We’ll test your mixtures by seeing which one can hold a paperclip, or even more. Let us see which mixture achieves the highest density!

Procedure

Background

Density refers to the amount of mass within a given volume of a substance. Materials with high density have more mass packed into a smaller space, while materials with low density have less mass spread over a larger volume. Ice, for example, is less dense than liquid water, which is why it floats. This principle plays a critical role in understanding the impact of melting ice caps on rising sea levels.

Ice caps, such as those in Greenland and Antarctica, store vast amounts of freshwater. When they melt due to rising global temperatures, the resulting water flows into the ocean, directly contributing to rising sea levels. This process adds volume to the oceans, displacing seawater and increasing global sea levels. Although melted ice is denser and occupies less volume than its frozen form, this relationship is irrelevant to sea-level rise because ice caps rest on land, and their melting adds entirely new water to the ocean.

The influx of freshwater from melting ice caps also disrupts ocean salinity and circulation patterns, influencing weather systems and marine ecosystems. Localized effects, such as changes in gravitational pull from shrinking ice masses, can temporarily lower sea levels in certain areas, but the global trend is an overall rise. These complexities highlight the urgent need to address the impacts of climate change on our oceans and coastal communities.

Before the Activity

• This project will span two days: Parts 1 and 2 are on Day 1 and Part 3 is on Day 2.
• Prepare your materials:
• Make copies of the Exploring Density Through Mixtures and Solutions Worksheet (1 per student).
• Make copies of the Making Sense Assessment (1 per pair of students).
• For each pair, have a beaker and a graduated cylinder with 25 mL of water mixed with 2 tablespoons of salt.
• Ensure the following supplies are available for students: vegetable oil, olive oil, salt, sugar, baby oil, corn syrup, liquid starch, and vinegar.
• Set up an area for students to test their mixtures and solutions in front of the whole class.
• Review and familiarize yourself with the vocabulary in the Assessment section.

During the Activity

Day 1

Part 1

1. Evaluate students' prior knowledge about density, mixtures, solutions, and the effects of different substances in water. For example, ask the following questions:

1. What happens if you drop a rock and a leaf in water? Why do you think one sinks and the other floats? (Answer: The rock sinks, and the leaf floats. This is because the rock is denser than water, meaning it has more mass packed into a smaller space, causing it to sink. The leaf is less dense and has more air trapped in it, making it float.)
2. What happens if you mix sand and water? Do they stay mixed or separate? (Answer: The sand and water will not stay mixed; they will separate. Sand is heavier (denser) than water, so it will eventually settle to the bottom. This demonstrates that sand does not dissolve in water, making it a mixture, not a solution.)
3. What happens if you mix sugar and water? Where does the sugar go? (Answer: When you mix sugar and water, the sugar dissolves, becoming invisible to the eye. The sugar molecules spread out evenly throughout the water, forming a solution. Even though you cannot see the sugar, it is still in the water, and the water will taste sweet.)

2. Explain the importance of understanding density and its environmental implications, such as the melting of ice caps. For example:

1. What is density? Density is how heavy something is for its size. Some things are light even if they are big, like a balloon. Other things are heavy even if they are small, like a rock. Think of it like this: If you had a big box of feathers and a tiny rock, the rock might be heavier than the whole box of feathers because it is denser!
2. Why does density matter in the world?
1. Water and ice: One cool thing about density is that it helps ice float! Ice is less dense than water, which is why icebergs float in the ocean.
2. Melting ice caps: But what happens when ice melts? The ice on the North and South Poles (the ice caps) is melting because the Earth is getting warmer. When the ice melts, it turns into water, which takes up more space in the oceans, making the water level rise. This can cause problems for animals such as polar bears, who live on ice, and for people living near the sea.

3. Go over the engineering design process with the students.
4. Define constraints for the students: “Constraints are like the rules or limits we need to follow when we do a project. Think about it like playing a game—there are certain things you can and cannot do. In this activity, we have some rules that help guide us to solve the problem.
5. Go over the constraints of the activity: time, materials, only two ingredients can be used, must fit in beaker, working in groups, etc.
6. Divide the students into groups of 2-3.
7. Ask: Explain the challenge: Each group is tasked with creating a mixture or solution that will be the densest, using the following substances:

• sugar
• vegetable oil
• olive oil
• vinegar
• baby oil
• corn syrup
• liquid starch

8. Imagine: With their groups, have students plan how they will create their densest mixtures or solutions by combining the given substances with their saltwater solution. They will need to choose two ingredients from the given list.
9. Have students record their brainstormed ideas in the “Imagine” section of their Exploring Density Through Mixtures and Solutions Worksheet.
10. Plan: Once each group has decided on one mixture/solution to test, have students sketch and label their plan in the “Plan” section of their Exploring Density Through Mixtures and Solutions Worksheet.
11. Create: Give students time to create their mixtures or solutions by carefully measuring and mixing their chosen substances with their saltwater solution. 

    

12. Have students record observations they make of their mixtures or solutions in the “Create/Observations” section of their Exploring Density Through Mixtures and Solutions Worksheet.
13. Have each group bring their mixture/solution to the testing area, where the entire class can see the testing.
14. Create a table on the whiteboard for all students to see that has a column for Group/Participants, a column for Mixture/Solution Contents, and a column for Results. (A similar table is in the “Test” section of the Exploring Density Through Mixtures and Solutions Worksheet.)
15. Have each student use the table in their worksheet to take notes during testing.

Part 2

16. Test: Conduct testing in front of the entire class.

• Choose one group to go first.
• Have one group member carefully place one paperclip at a time into their mixture or solution. They should continue adding paperclips one by one until the mixture or solution can no longer support them, and all the paperclips sink to the bottom. 

  

• Have all students record the number of paperclips the mixture or solution held before sinking on their worksheet.
• Repeat these steps for each group, one at a time.

17. Analysis: As a class, look over the results and answer the following together:

• Why do certain mixtures hold more paperclips?
• Density of the substances: Students might notice that mixtures with thicker or heavier liquids (such as corn syrup or baby oil) held more paperclips because those liquids are denser.
• Layering of substances: Some students might point out that certain mixtures separated into layers (such as oil and water), which may have impacted how many paperclips the mixture could hold.
• Dissolving of substances: Students might say that substances such as sugar dissolved completely, changing the mixture and making it harder to support the paperclips.
• What happened when the paperclips interacted with the solutions/mixtures?
• Thickness or viscosity: Students may observe that thicker liquids (such as corn syrup) resisted the weight of the paperclips longer, while thinner liquids (such as vinegar) allowed the paperclips to sink faster.
• Mixing or separation: Some students may notice that mixtures where the substances did not mix well (such as oil and water) could still float paperclips on top of one layer, while fully mixed solutions behaved differently.
• Why do you think we got these results?
• Differences in the substances: Students might suggest that some mixtures were able to hold more paperclips because the liquids used (such as corn syrup) were heavier or denser compared to lighter ones (such as oil).
• How well the substances combined: Students might say that mixtures that stayed combined (solutions) may have behaved differently from those that separated (mixtures), impacting how well they could hold paperclips.
• Amount of each ingredient: Some groups may realize that adding more of a dense substance such as sugar or corn syrup might have made their mixture denser and better at holding paperclips.

Day 2

Part 3

1. Improve: Let students know they will have the chance to improve their mixtures or solutions. Encourage them to think about how they can make their mixture denser to hold more paperclips.
2. Have students write down what they want to change or improve in their mixtures and solutions in the “Improve” section of the Exploring Density Through Mixtures and Solutions Worksheet.
3. Give students time to re-create and improve their mixtures based on their observations and reflections from testing. Note: They can add or change the amounts of ingredients to increase the density. Their goal is to increase the density and support more paper clips.
4. Retest: Test the improved mixtures by conducting the paperclip test with them.
5. Have students complete the table in their worksheet with their retested results. Encourage them to compare these new results with their original test.
6. Reflection: As a class, discuss the overall findings of the activity.

• Summarize the findings:
• Mixture density: Groups that used denser substances (such as corn syrup or baby oil) were able to hold more paperclips, while those using less dense substances (such as vinegar or oil) held fewer.
• Layering vs. mixing: Some groups found that mixtures with separated layers (such as oil and water) behaved differently than fully mixed solutions, affecting how many paperclips could float.
• Solubility effects: Substances such as sugar dissolved completely, creating solutions that were more consistent in density, but not necessarily better at supporting paperclips.
• Discuss the implications of density in real-world scenarios, such as oceanic changes due to melting ice caps.
• Ice and water density: The experiment illustrates why ice floats in water—ice is less dense. This principle is important in understanding ecosystems in polar regions, where animals rely on floating ice for survival.
• Melting ice caps: As ice caps melt due to global warming, the water that was once trapped in ice increases the volume of the oceans. This can lead to rising sea levels, which impacts coastal communities, flooding habitats and affecting species such as polar bears that depend on ice.
• Ocean circulation: Changes in the density of seawater (due to melting ice or temperature changes) can also affect ocean currents, which play a critical role in regulating Earth's climate.

Vocabulary/Definitions

density: A substance's mass per unit of volume.

mixture: A material made up of two or more different chemical substances that are not chemically bonded.

solution: A mixture where one substance is dissolved in another.

Assessment

Pre-Activity Assessment

Brainstorming: In small groups, students engage in an open discussion about what is causing our sea levels to rise. Answers could include melting ice caps, melting glaciers, melting ice sheets, loss of sea ice, or global warming.

Table Groups: Students watch a two-minute NASA time-lapse video and, as a class, discuss what they believe is happening. Responses could include: The ice is disappearing as the years progress, or ice is melting into the ocean. You may refer to the sentence stems below to help support struggling learners:

Sentence Stems:

• I think _____________ is happening because _______.
• I predict that _________ because ________.
• I noticed that ________________. Therefore, I think __________.

Activity Embedded (Formative) Assessment

Engineering Design Process: Students work through the engineering design process in their Exploring Density Through Mixtures and Solutions Worksheet.

Post-Activity (Summative) Assessment

Class discussion: To summarize the testing and retesting results, have a class discussion to discuss the findings and the implications of density in real-world scenarios, such as oceanic changes due to melting ice caps.

Making Sense Assessment: Have students reflect on the science concepts they explored and/or the science and engineering skills they used by completing the Making Sense Assessment.

Activity Scaling

• For lower grades, you can do this activity as a whole group.
• For upper grades, you can have them do an extension activity where they create their own recipes of mixtures and solutions using safe alternative liquids.

Copyright

Contributors

Supporting Program

Acknowledgements

This curriculum was developed under National Science Foundation through the Center for Dynamics and Control of Materials: an NSF MRSEC under Cooperative Agreement number DMR-1720595. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.