What is Heat Transfer?

This lesson developed by Mark Palmer from CAPS

Recommended Age: Upper Elementary

Guiding Questions

1. What is "heat transfer"? How does it affect our weather?
   
   
2. How does radiation heat transfer happen?
   
   
3. How does conduction heat transfer happen?
   
   
4. How does convection heat transfer happen?

Objectives

Concepts:

• Heat is warmth. In this lesson, we are dealing with heat or warmth from our sun.
  
  
• Radiation is the method by which the sun's energy reaches the earth.
  
  
• Conduction is the direct transfer or movement of warmth and energy from one molecule to another molecule by collision.
  
  
• Convection is the organized motion or movement of large groups of molecules based on their relative densities or temperatures.

Principles:

• Heat from the sun moves by way of waves.
  
  
• There are three methods by which heat transfer happens: radiation, conduction, and convection.

Facts:

• "Weather" happens as the result of heat transfer in our atmosphere.
  
  
• Radiation is the heat from the sun that travels in the form of waves.
  
  
• Radiation or heat waves pass most easily through a vacuum.
  
  
• In conduction, the faster molecules are moving, the hotter the substance will be.
  
  
• Convection is happening when warm air rises and cold air sinks.

Skills

• Making Observations
• Making Comparisons
• Communicating Findings
• Making Inferences
• Drawing Conclusions

Materials

1. Warm surface
2. Candle & matches
3. Scissors
4. Paper
5. Tape
6. String
7. Handout #1
8. Handout #2

Room Preparation: No preparations necessary.

Safety Precautions: Be careful when handling and using candles, other heat sources, and scissors.

Procedures and Activity

Introduction

1. What makes "weather" happen?
   Lead discussion to fact that our weather is the result of the changes in temperature and "heat transfer" in our atmosphere.
   
   
2. What is "heat transfer?"
   Discuss the two separate words "heat" and "transfer" and come up with some definitions and understandings. For example, heat is warmth and transfer means movement or traveling. In this lesson, we are talking about how heat moves and warms up different surfaces and the air.
   
   
3. How does heat transfer happen?
   Heat is transferred by three methods we are going to learn about today:
   • Radiation
   • Conduction
   • Convection
   
   
4. Pass out handout #1 and review what we are going to study and take notes on today.

Activity #1: Experiencing "Radiation"

1. Go outside to a shady location. Stand for a few minutes and think about what you feel. Is it hot? Is it cool or cold? Can you feel your body absorbing the sun's energy and heat?
   
   
2. Move to a sunny location. Stand for a few minutes and think about what you feel. Is it hot? Is it cool or cold? Can you feel your body absorbing the sun's energy and heat? How do you feel?
   
   
3. What is happening? We are experiencing "radiation" or the method by which the sun's energy reaches the earth. The sun's energy travels in waves. When we feel the sun's warmth, we are feeling the sun's energy or waves touching and warming up our "surface."

Activity #2: Experiencing "Conduction"

1. Find an outdoor wall or surface that has been absorbing the sun's energy or waves.
   
   
2. First, use the palm of your hand to feel your cheeks. Make a mental note of the warmth or coolness you feel or the temperature of your hand on your cheek.
   
   
3. Now place the palm of your hand against a warm surface or wall. Keep your palm on the wall or surface until your palm absorbs heat and feels warmer than before.
   
   
4. Take your palm away from the surface and feel your cheek. How does this temperature compare with the first time you touched your cheek?
   
   
5. What did you do and what happened to make your palm feel warmer after you laid it on the sunny wall or surface?

6. What is happening? We are experiencing "conduction" or the direct transfer or movement of warmth and energy from one molecule to another molecule by collision.

Activity #3: Experiencing "Convection"

1. Pass out handout #2, along with scissors, a piece of string, and tape.
   
   
2. Instruct and demonstrate how to cut the hand-out circle into a spiral.
   
   
3. Everyone should make spirals out of their hand-outs.
   
   
4. Model and have everyone attach the string to the center of the spiral with tape.
   
   
5. Light candles. Review safety precautions and do not touch flame, tip over candle, or let paper spirals touch flame.
   
   
6. Demonstrate and have everyone hold their spirals over candles. (Note: you may use another heat source such as a space heater or heat lamp.)
   
   
7. Hold the spiral still. After a few moments, see what happens. The spiral should begin to spin. Observe its direction of movement.
   
   
8. What is happening? We are experiencing "convection" or the organized motion or movement of large groups of molecules based on their relative densities or temperatures.

Closing - Original Questions

Ask Again:

1. What makes "weather" happen?
2. What is "heat transfer?"
3. How does heat transfer happen?

Evaluation

• Listen for an understanding of the fact that our weather is the result of the changes in temperature and "heat transfer" in our atmosphere.
• Listen to hear definitions and understandings for "heat" and "transfer."
• Let students define and explain the three different methods of "heat transfer": radiation, conduction, convection

Extension Ideas

1. What are some other examples of when we see radiation, conduction, and convection heat transfer happening?
   
   
2. Can we think of how we might use different forms of heat transfer?
   Research or share ideas about solar energy to heat homes, water in swimming pools.
   Learn about convection ovens and how they work.
   
   
3. When do we see evidence of heat transfer in our everyday lives? Examples:
   • Feeling heat and suffering heat strokes on a hot day. Share caution exercised by construction workers, people on the beach, etc. on hot days.
   • Walking barefoot on dark pavement on a hot day and risk of burning soles of feet.
   • Melting of ice on a lake or pond and risks for ice skaters or ice fishermen.
   • Sudden change of temperature and storms coming in.
   • Heat in a closed car or room and danger for people and animals.
   
   
4. Look over other activities from CAPS: Does the Sun Influence the Temperature of the Earth?, Reading a Thermometer, Keeping a Daily Weather Log, Convection in Our Atmosphere, and What is Temperature?

Prerequisite Vocabulary

Conduction

The direct transfer or movement of warmth and energy from one molecule to another molecule by collision.

Convection

The organized motion or movement of large groups of molecules based on their relative densities or temperatures.

Heat Transfer

The movement or passing of warmth from one point to another.

Radiation

The method by which the sun's energy reaches the earth.

Weather

The state of the atmosphere and conditions such as dry or wet, cold or hot, stormy or calm, cloudy or clear.

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