Using Solar Energy

Part of the Climate Change exhibition.

Labeled drawing of a flask partially filled with water with a thermometer partly immersed, held in place by one hole rubber stopper at top of flask

Grades: 6-12
Time Frame: 45 minutes

When fossil fuels burn, carbon dioxide is released. This increasing greenhouse gas is causing more and more heat to be absorbed and held in Earth's atmosphere, leading to warming global temperatures. If we could produce more of our energy from "clean" and renewable energy sources such as the Sun, wind, or water, we could reduce carbon dioxide emissions and slow global warming.
In this activity, students will demonstrate how solar energy can be used to heat water. As an extension, students can design their own "clean" energy project.

Students will:

  • understand energy choices that communities and governments can make to address climate change


  • observation
  • experimentation
  • data collection


  • A copy of student worksheets for each team
  • For each student team:
  • flask
  • 1-hole rubber stopper
  • thermometer
  • petroleum jelly
  • sunny window or a 150-watt light source

Prior Knowledge:

  1. Engage the students in a discussion of energy that they use in their daily lives, and that the energy comes from a variety of sources. You and/or your students can consult your local electricity providers' websites to find out what fuels are used to generate their electricity (e.g., how is your school heated, and what energy or fuel is used to heat the water in your school?)
  2. Tell students that in this experiment, they will demonstrate how solar energy can be used to heat water. They will then design their own alternative energy project.


  1. Divide the class into teams of two students.
  2. Distribute the instructional worksheet and materials to each student team.
  3. Have students apply a small amount of petroleum jelly to the bulb end of the thermometer and insert the thermometer into the hole of the stopper. Gradually rotate the thermometer as your push it through the hole in the stopper. Be careful not to apply a bending force to the thermometer, this may cause the thermometer to break.


  1. Once student teams have concluded their observations and analysis, have a class discussion that reviews their answers. See the answer key below.

Extension Activity
Set up a design challenge, for example:

  • Teams create a more efficient collector of solar energy to heat the water (e.g., create reflectors or lenses that concentrate the Sun's rays on the water or the container; darken the water or the water container so more of the energy is absorbed by the system).
  • Teams compete to produce a solar device that would heat a given volume of water to the highest temperature in 20 minutes. Limit the materials to simple items such as aluminum foil, black paint, and cardboard.
  • Teams design a device that would capture the Sun's energy to perform a task other than heating the water in a flask (e.g., create an oven to bake food, a system to distill water, or a system to increase the amount of energy produced by a photovoltaic cell).

Answer Key

  1. What are some possible uses for solar energy? Look at the results of your experiment to help you answer this question. (Answer: Heating water, heating homes.)
  2. Why is solar energy safer for the environment than energy obtained from fossil fuels? (Answer: No greenhouse gases enter the atmosphere.)
  3. Describe other energy sources. List the advantages and disadvantages of each. Use resources in your school library and the Climate Change exhibit to help you answer this question. (Answers will vary.)
  4. Solar energy is now being used in some places to generate electricity. Research where and how this is done. (Answers will vary.)
  5. Design an invention that can be powered by solar energy. Describe how it would work. (Answers will vary. An example is the solar cell.)

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