Ask students what may be causing sea levels to rise around the globe and they will probably say that the ice caps are melting due to global warming.  What students may not know is that glacier ice is not the only contributing factor to this phenomenon. Through this lesson, students have the opportunity to explore a property of water known as thermal expansion that is a significant factor contributing to sea levels rising.


“Science is more than a body of knowledge and a way of accumulating and validating that knowledge.”[1] This bold statement comes from Science for All Americans, a collaborative effort among scientists and other professionals known as the American Association for the Advancement of Science (AAAS). Science for All Americans outlines what all students should know related to mathematics, science, and technology before they graduate high school, so that they are knowledgeable citizens who can make informed decisions about the world around them. Much of the text focuses on students experiencing the nature of science. But, what exactly is the nature of science? It can best be explained by peering into the world of a scientist. Imagine a scientist who sits in his office with a group of college students who are analyzing data they have been collecting all summer long. They are using every ounce of brainpower they collectively have to hypothesize an explanation for the unexpected results from their data. One student asks the question, “Could this oddity be used as a marker to determine the rate of degradation in landfills?” The scientist pauses for a moment and asks the other students what they think. One student says, “Don’t we have to make sure what we are seeing is not due to human error or contamination.” “Yes,” another student pipes up. “Why don’t we re-run the tests and see if we get the same biological marker in those results?” Excitement is apparent on their faces as they begin to plan to re-run their tests.

Could what they are working on be an answer to a question scientists have been looking at for years? They certainly cannot jump to conclusions. However, they are experiencing the excitement of the nature of science; a process that transcends the lab. It is a process experienced by people on a daily basis who explore the unknown or, at the very least, the uncertain. The nature of science is a process that enhances independent thinking skills and demands the use of prior experiences and knowledge. For this reason, science should not be told to students; it should be experienced. In the lesson, Hot Mama, students experience the nature of science. The lesson begins with students exploring a lab set-up, followed by a discussion of the main concept being studies. The lesson culminates with an application activity that links students to a real world issue.  Students learn about thermal expansion through the nature of science.

Hot Mama begins with student exploration, and, like with any exploration, the teacher sets up materials associated with a question, or a series of questions, to be investigated by students. Students may be asked to manipulate the materials, make observations and collect data.  According to The AAAS, “The essence of science is validation by observation.” In the exploration of Hot Mama, students observe what happens to the level of chilled water as it warms. Within moments, students see the water level rising in their experiment. Facilitating the process, the teacher’s primary role is focusing students on their observations and occasionally leading the students to consider why the water is rising.

Students are now ready for an explanation for the observations they just made. In this phase of the lesson, students can begin to explain some of the observations that occurred during the exploration. The explanations associated with those observations come from student discussion lead by the teacher. The teacher facilitates the discussion by asking guiding questions connected to the data they collected through observations. One such question could be, “Is there any correlation between temperature and the level of water?” Students can achieve understanding of the concept through explaining the data and observations that resulted from watching the chilled water warm. In the explanation section of the lesson students, should be introduced to the correct terminology associated with the concept they are learning through the investigation. In Hot Mama, students are actually experiencing thermal expansion, a concept that is the cause agent for the water rising in the experiment. As the water warms, the water molecules begin expanding because as they warm, they increase in movement. This movement creates more space between water molecules, causing the water level to rise. Students then put their understanding of thermal expansion to use analyzing how global warming impacts sea levels. Students analyze two graphs embedded in the lesson that depict the average change in the global climate and average changes in sea levels. Because students are able to see through exploration, that an increase in temperature causes water to expand and rise and because the teacher is able to explain thermal expansion as the underpinnings to their observations, students can analyze the two graphs and feel confident that they know why the sea levels are rising.

Once the teacher concludes that students have achieved a thorough understanding of the concept presented through exploration and explanation, the teacher can begin to move students into secondary investigative problems, extension readings, or anything else that could be associated with the concept they just learned. Hot Mama has students look at maps from an application on Google maps called, “sea levels rising”. (The maps are provided as student handouts if teachers are unable to access the application on Google). The maps allow students to view landmasses and visualize the amount of land that is overtaken by seawater when sea levels rise. By allowing students to explore a real world issue, like the impact of global warming on landmasses, they gain further insight into the nature of science and why scientists pursue careers in science. “Science, energetically pursued, can provide humanity with the knowledge of the biophysical environment and of social behavior needed to develop effective solutions to its global and local problems; without that knowledge, progress toward a safe world will be unnecessarily handicapped”.[2]

Structuring lessons so that they consist of the processes of exploration, explanation, and application, allows students to experience the nature of science just as the college students did who were studying landfill degradation at the top of the article. As the college students sat around their professors’ office and began to evaluate the data they had spent the entire summer collecting, they were not only utilizing logical thinking skills but they were excited about their possible discovery. They were excited because the data had personal meaning to them. They had worked hard to build their own knowledge base of the subject and they owned every piece of what they were studying. Students at any level can have this same experience if they are lead by teachers through explorations, explanations, and applications. This is the nature of science that should be experienced so that as citizens, they are able to think critically and make informed decisions about the world around them. “Students cannot learn to think critically, analyze information, communicate scientific ideas, make logical arguments, work as part of a team, and acquire other desirable skills unless they are permitted and encouraged to do those things over and over in many contexts.”[3] Science for all Americans is possible through student experiences like Hot Mama.


1. Engage

a. Sea Levels Around the Globe [10 minutes] – Students look at data from global average Sea Levels according to NASA.

2. Explore

a. Thermal Expansion Lab [30 minutes] – Through a laboratory experiment students explore what happens to chilled water as it warms.

3. Explain

a. Thermal Expansion [15 minutes] – Students gain an understanding of the underlying concept that causes water to expand when it warms.

4. Extend

a. What Causes the Sea Levels to Rise? [10 minutes] – Students discuss factors that impact sea levels rising including thermal expansion of water.
b. What Future Impact will the Sea Levels Have? [20 minutes] – Students analyze projection maps from Google Earth to gain perspectives on the global impact of the continuation of sea level rising.


Food coloring
Stop watch or timer (online timers can be used and projected on a SmartBoard or screen)
Ice water bath or access to a refrigerator
Flask (example in the image is a 250 mL flask, but any size can be used)
Rubber Stopper (example in the image is a #5 stopper but with a smaller flask you should choose a rubber stopper that fits that flask)
The rubber stopper should have two holes
Glass tubing (The tubing should be long enough to reach the water that will be placed in the flask)

Student Objectives

Students will…

Explore the thermal expansion of water.
Gain an understanding of why water expands as it warms.
Practice observation skills.
Connect thermal expansion to sea levels rising.
Analyze graphical representations of rising sea levels.

Lesson Preparation

  • Use Vaseline to place a thermometer and a glass rod in a stopper.
    • Place enough water in the flask so that when the stopper is on the flask the glass rod and thermometer are touching the water.
      • Place 2 drops of food coloring in the flask with the water so students can see the water better.

Make sure the seal is tight

  • Prepare an ice water bath and place the flasks with water in the ice water bath 20-30 minutes prior to class



Sea Levels Around the Globe [10 minutes] – Students look at data from global average Sea Levels according to NASA.

  • Begin this activity by asking students the following question:

“Are sea levels rising?”

  • Once students give their responses present them with the following data.

  • Once students have analyzed the data ask them the question again, “Are sea levels rising?”
  • Student responses should be YES according to the data they are looking at.

Then ask students “What causes the sea levels to rise?”

  • Student responses will probably center on “ice caps” melting.
  • Explain to students that they will be conducting a lab experiment to explore another factor that could be contributing to sea levels rising.


Thermal Expansion Lab [30 minutes] – Through a laboratory experiment students explore what happens to chilled water as it warms.

  • Give students Handout 2 and explain to them that they will use the document to record data from today’s activity.
  • Then have students retrieve the supplies you set up earlier for this activity
    • Each group of students should have the following materials:
      • A chilled flask of colored water
      • A stopper to fit the flask with a thermometer and a glass rod inserted in the stopper
      • Ask students to place the stopper in the flask and make sure that both the thermometer and the glass rod are in the water. (The tip of the glass rod should be immersed in the water.)
      • Have students observe the experimental set up and record observations related to water in the glass tube and temperature.
      • Then ask students to answer the questions on the handout.
Temperature (Celsius) Observations
2 minutes
4 minutes
6 minutes
8 minutes
10 minutes
12 minutes
14 minutes


Thermal Expansion [15 minutes] – Students gain an understanding of the underlying concept that causes water to expand when it warms.

In this section of the lesson explain to students the concept of thermal expansion, but begin by asking the class…

“Why did the water rise up the glass tube?”

  • Give students plenty of time to give their explanations and then explain the concept of thermal expansion

Particles move faster and faster and begin to separate as temperature rises. This occurs with solids, liquids, and gases. As the temperature of the water rises, the water molecules begin moving faster, bumping into each other. This causes separation and leads to the concept of expansion.

  • Another example of thermal expansion is the liquid that is rising in the thermometer. The liquid mercury in the thermometer is warming; particles are moving faster and separating, creating the rise in the line on the thermometer.
  • If students are having a difficult time grasping this concept do the following demonstration with them:
  • Have 5-6 students stand and get into a group as tight as they can. Then ask them to begin jumping. This will demonstrate the concept that as particles begin moving around the create space.


What Causes the Sea Levels to Rise? [10 minutes] – Students discuss factors that impact sea levels rising including thermal expansion of water.

Student have seen data from NASA and have explored thermal expansion first hand. Lead students through a short discussion on why the sea levels are actually rising.

  • Although there are many factors, the conclusion that we are leading students to in this discussion is that the increased temperature of the earth is directly impacting the temperature of the water. In turn, the water is literally expanding.
  • There are many other factors to consider in this argument as well. Keep a running list of those factors. As you discuss topics that are relevant to those factors, connect students back to this experience.


What Future Impact will the Sea Levels Have? [20 minutes] – Students analyze projection maps from Google Earth to gain perspectives on the global impact of the continuation of sea level rising.

Use the application in Google maps, “Sea Levels Rising”, to explore the impact that rising sea levels have on coastal regions around the world.

Accessing sea levels rising maps on Google maps:

  1. Go to Google maps
  2. Go to my maps
  3. Go to browse directory
  4. Search maps and select sea levels rising


Appendix A [Download to see handouts.]provides images of Puerto Rico and Massachusetts taken from Google maps that students can view and analyze if the teacher doesn’t have access to the Google maps website for sea levels rising.


  • Brochure: Have students create a pamphlet with information they have learned about sea levels rising and global impact. Then ask students to share their pamphlet with other students, parents, or community members to provide information on the topic.
  • Infographic: Have students create info graphic over sea levels and their impact (an info graphics is a graphical representation of information on a topic).
    • An example is provided in Appendix B. [Download to see handouts.]

Global Connections

  • Webcam with a classroom located in a coastal region and allow students to gain their perspective on the impact of sea levels rising.


Process and Inquiry Standards and Objectives for Physical Science:

Process Standard 1: Observe and MeasureObserving is the first action taken by the learner to acquire new information about an object or event. Opportunities for observation are developed through the use of a variety of scientific tools. Measurement allows observations to be quantified. The student will accomplish these objectives to meet this process standard.

1. Identify qualitative and quantitative changes given conditions (e.g., temperature, mass, volume, time, position, length) before, during, and after an event.

2. Use appropriate tools (e.g., metric ruler, graduated cylinder, thermometer, balances, spring scales, stopwatches) when measuring objects and/or events.

3. Use appropriate System International (SI) units (i.e., grams, meters, liters, degrees Celsius, and seconds); and SI prefixes (i.e. micro-, milli-, centi-, and kilo-) when measuring objects and/or events.

Process Standard 3: Experiment – Experimenting is a method of discovering information. It requires making observations and measurements to test ideas. The student will accomplish these objectives to meet this process standard.

1. Evaluate the design of a physical science investigation.

2. Identify the independent variables, dependent variables, and controls in an experiment.

3. Use mathematics to show relationships within a given set of observations.

Process Standard 4: Interpret and Communicate – Interpreting is the process of recognizing patterns in collected data by making inferences, predictions, or conclusions. Communicating is the process of describing, recording, and reporting experimental procedures and results to others. Communication may be oral, written, or mathematical and includes organizing ideas, using appropriate vocabulary, graphs, other visual representations, and mathematical equations. The student will accomplish these objectives to meet this process standard.

1. Select appropriate predictions based on previously observed patterns of evidence.

2*. Report data in an appropriate manner.

3. Interpret data tables, line, bar, trend, and/or circle graphs.

4. Accept or reject hypotheses when given results of a physical science investigation.

5. Evaluate experimental data to draw the most logical conclusion.

6*. Prepare a written report describing the sequence, results, and interpretation of a physical science investigation or event.

7*. Communicate or defend scientific thinking that resulted in conclusions.

Process Standard 6: Inquiry – Inquiry can be defined as the skills necessary to carry out the process of scientific or systemic thinking. In order for inquiry to occur, students must have the opportunity to ask a question, formulate a procedure, and observe phenomena. The student will accomplish these objectives to meet this process standard.

*1. Formulate a testable hypothesis and design an appropriate experiment relating to the physical world.

*2. Design and conduct physical science investigations in which variables are identified and controlled.

*3. Use a variety of technologies, such as hand tools, measuring instruments, and computers to collect, analyze, and display data.

*4. Inquiries should lead to the formulation of explanations or models (physical, conceptual, and mathematical). In answering questions, students should engage in discussions (based on scientific knowledge, the use of logic, and evidence from the investigation) and arguments that encourage the revision of their explanations, leading to further inquiry.

Content Standards and Objectives for Physical Science:

Standard 1: Structure and Properties of Matter – All matter is made up of atoms. Its structure is made up of repeating patterns and has characteristic properties. The student will engage in investigations that integrate the process standards and lead to the discovery of the following objectives:

3. Matter has characteristic properties, such as boiling points, melting points, and density, which distinguish pure substances and can be used to separate one substance from another.

[1]American Association for the Advancement of Science. (1990). Science for all Americans. New York: Oxford University Press.

[2] Ibid.

[3] Ibid.