Science Concepts—Thermal Expansion

Summary: As the ocean’s temperature increases, its volume expands. In this topic guide, students use a model to demonstrate the relationship between water temperature and volume, and then use their findings to describe the impact a warming ocean has on sea level.

Concepts to teach:


  1. Heated water has more volume than cooler water due to a process called thermal expansion.
  2. Thermal expansion is the primary cause of climate induced sea level rise.
  3. A model can demonstrate a scientific concept.

Standards: NGSS Performance Expectations

  • MS-PS1-4. Develop a model that predicts and describes changes in particle motion, temperature, and state of a pure substance when thermal energy is added or removed.

Specific Objectives:
Students will be able to:

  1. Demonstrate that heated water has more volume than cooler water due to a process called thermal expansion
  2. Explain how sea level rise results in part from thermal expansion.
  3. Use a model to demonstrate a scientific concept.

Activity Links and Resources:

  • COSEE’s Thermal Expansion and Sea Level Rise—In this experiment, students measure the relationship between water volume and water temperature. This activity can be performed as a demonstration, or at the high school level, in student groups.


  • What happened to the water level as the temperature increased?
  • What caused the water level in the flask to change over time?
  • Would salt water react the same way as fresh water? How could you design an experiment that would test your hypothesis?