Hands-on Activity: Heat It Up!
Educational Standards :
Pre-Req Knowledge (Return to Contents)
Familiarity with the Sun's composition, layers and importance as Earth's energy source, as provided in the Blazing Gas lesson of this Solar System unit.
Learning Objectives (Return to Contents)
After this activity, students should be able to:
Materials List (Return to Contents)
To share with the entire class (teacher demonstration):
Introduction/Motivation (Return to Contents)
Can heat move? Of course it can. Heat (energy) travels in three ways: convention, conduction and radiation. Conduction works by direct contact of two materials. This is what happens when a pot is placed on the stove. First the stove material is heated. Then the heat is transferred by conduction to the pot, which is in direct contact with the hot stove. Convection works through the interaction of fluid molecules such as air or water. Convection typically occurs when a hot fluid or gas moves upward. Radiation works through the movement of heat waves. This is similar to light and radio waves.
So, how does heat get from the Sun to Earth? Conduction and convection require a material (either solid, liquid or gas) to be present. (Emphasize: Since there is no matter in space between the Sun and Earth, all the heat from the Sun comes to us in the form of radiation.) Inside the Sun is matter and therefore other forms of heat transfer are at work. The Sun uses two methods to transport energy out from the interior. The first is radiation. Radiation begins in the Sun's core. In the Sun's radiation zone, heat from the core travels as electromagnetic waves (radiation) outwards to the Sun's convective zone. Convection currents are currents created when there are differences in temperature and density. (Emphasize: Warmer liquids and gasses are less dense and therefore float (or rise) when in cooler liquids and gasses.) ) As this warmer gas (or liquid) rises, cooler gas (or liquid) moves to take its place where it is heated. This is called a convection current. Convection currents swirl the energy until it passes through to the Sun's photosphere.
When the Sun's energy (in the form of radiation) hits our planet's atmosphere, some of it reflects off while some of it heats up the air, water and land. Once the material that makes up the Earth and its atmosphere is heated, it can move around the globe through convection and conduction. Heat loss through a wall is an example of conduction. Insulation limits conduction and keeps the heat inside your house. Cooling yourself with a fan is an example of convection. Convection is the reason it feels colder on a windy day.
Engineers must understand how heat moves so that the devices they build do not get too hot or too cold. What would happen if an engineer did not make sure there was insulation in the walls of your house? It would be very cold inside on a winter day because the heat could escape through conduction. What would happen if the cord to an appliance did not have an insulated covering on it? The wire would be exposed and the electricity running through it could hurt someone or start a fire. What would happen if an engineer wrapped an engine in insulation? The heat generated by the engine would not be able to get out and the engine would overheat.
Table 1 provides examples of convection, conduction and radiation on the Sun and on Earth. It may be helpful to draw the table on the board as a way to graphically organize and distinguish the concepts.
Vocabulary/Definitions (Return to Contents)
Procedure (Return to Contents)
Before the Activity
With the Students
Attachments (Return to Contents)
Safety Issues (Return to Contents)
Troubleshooting Tips (Return to Contents)
It works best to drop the glitter and food coloring from directly above the heat source.
If the water takes a long time to heat, either lower the dish or remove some water.
Assessment (Return to Contents)
Discussion Questions: Ask students what they know about heat movement. Can heat move? If it can, how does it move? Introduce the concepts of conduction, convection and radiation. When do they see these kinds of heat transfer in their daily lives? Real-life examples: Sunburn is radiation from the Sun moving 93 million miles (150 million km) through space to heat your skin. The outside of a mug of hot cocoa is warm because the heat in the liquid is moving to the outside of the mug through conduction. The fact that the water on the surface of a swimming pool is warmer than the water in the deep parts is caused by convection.
Activity Embedded Assessment
Voting: Before starting the class demonstration, ask the students to vote on the following question. Tally votes on the board. Tell the students that the question will be answered during the demonstration.
Numbered Heads: Divide the class into teams of three to five students each. Have the students on each team number off so each member has a different number. Ask the students a question and give them a time frame for solving it (~one minute). The members of each team should work together to answer the question. Everyone on the team must know the answer. Call a number at random. Students with that number should raise their hands. If not all the students with that number raise their hands, give the teams a little more time. Ask the students:
Activity Extensions (Return to Contents)
Take temperature measurements at several different heights above the surface of the water so the students can see how the temperature changes as you move away from the Sun. Have them draw a picture of the experiment and color code the temperatures at different locations.
Assign student pairs different rooms of a house or school, or different venues or activities, such as stores, recreation centers, transportation, cooking or sports. Give them each 15 minutes to brainstorm a list of engineer-designed devices or products that would be found in that place or activity, in which understanding the three ways of heat transfer was important for them to work. Have the student teams report back to the entire class on their findings.
Activity Scaling (Return to Contents)
References (Return to Contents)
Kagen, Spencer. Cooperative Learning. San Juan Capistrano, CA: Kagan Cooperative Learning, 1994. (Source for Numbered Heads assessment)
Wilson, Jim (editor). NASA. Last updated January 12, 2007. National Aeronautics and Space Administration. Accessed January 15, 2007. http://www.nasa.gov/
ContributorsJessica Todd, Geoffrey Hill, Jessica Butterfield, Denise W. Carlson
Copyright© 2006 by Regents of the University of Colorado. This digital library content was developed by the Integrated Teaching and Learning Program under National Science Foundation Grant No. 0338326.
Supporting Program (Return to Contents)Integrated Teaching and Learning Program, College of Engineering, University of Colorado at Boulder
Last Modified: December 11, 2013