In this Investigation, students will continue their study of heat. They will focus on how the body controls its temperature.

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A. Begin the lesson by reviewing what students have learned about heat in Investigations One through Three. Tell students that one way to present what they have learned is to create a diagram or a concept map. Guide students in creating a concept map focused on heat.

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1. To begin, write the term heat on the board as a title to the concept map. The concept map will be continued in Investigation Five.

2. Ask students: What large concepts or ideas have you focused on during the first three Investigations? Student answers will vary. Students should suggest that they have studied heat transfer, kinetic energy and temperature, and heat and reactions. 

Determine three or four major concepts and create headings on the board to represent these concepts. Leave enough space between the headings to place text around each heading.

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1. To begin, write the term heat on the board as a title to the concept map. The concept map will be continued in Investigation Five.

2. Ask students: What large concepts or ideas have you focused on during the first three Investigations? Student answers will vary. Students should suggest that they have studied heat transfer, kinetic energy and temperature, and heat and reactions. 

Determine three or four major concepts and create headings on the board to represent these concepts. Leave enough space between the headings to place text around each heading.

3. Choose one heading to focus on first. For example, you may choose to focus on kinetic energy and temperature. 

Ask students: What did you learn about kinetic energy and temperature? What conclusions did you draw? What are some main ideas about kinetic energy that you think are important? Student answers may vary, but may include the following: (1) heat is transferred from molecules with more kinetic energy to molecules with less kinetic energy and (2) as kinetic energy increases the temperature of a substance increases. 

As students suggest responses, record their ideas under the kinetic energy and temperature heading.

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Students do not have the graphic below:

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Students do not have the graphic below:

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B. Tell students that in Investigation Four, they will continue their exploration of heat, this time focusing on heat and the body.

1. Ask students the following questions to promote discussion:

Ask students: What do you know about heat and the body? Student answers will vary. Students may respond that our bodies give off heat, that excessive heat is harmful to the body, or that normal internal body temperature is 98.6°F (37°C).

Ask students: How do you know that the body produces heat? Student answers may vary. Students may have felt the body heat of another person when standing close to someone, they may have felt a room get warm with many people present, or they may have blown on their cold hands in the winter in order to warm them.

2. If students have not suggested it, tell them that the body has a small range of temperatures at which it is able to function.

a. Ask students: What is normal body temperature? Student answers may vary.

b. Tell students that normal body temperature is approximately 37°C (98.6°F). If the body temperature remains between approximately 36°C and 39°C (96°F and 103°F) it is able to function. Outside of these temperatures, the organs in the body are unable to function as effectively or efficiently as they normally do.

3. Explain to students that their bodies are equipped with an internal body temperature sensor, which communicates to the brain when their bodies are too warm or too cold. The brain then automatically determines what is an appropriate way to reach it’s normal temperature range.

4. Ask students: Do you think your body is able to do anything to control its temperature? Can your body do anything to change the heat that is transferred from it? Student answers will vary.

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5. Encourage students to discuss these questions further. Ask them the following questions to promote discussion of body temperature and ways to control it:

a. Ask students: What do you do when you become too cold? Student answers may vary. Students may put on more clothing, find shelter and heat, rub their hands together, or stand close to other people in a group.

b.  Ask students: Can you think of any automatic responses of your body? Are there things your body does that you do not control when you are cold? Student answers may vary. Students may recall that they shiver when they are cold, that their lips turn blue, and that sensation in their fingers and toes is decreased.

c. Tell students that when their bodies become too cold, the body automatically determines which parts are most important to keep warm. Most of the body’s important organs are in the torso, or abdomen, and in the head (brain), and the body automatically chooses to send most of the blood there to ensure that the vital organs are able to function. This causes fingers and toes to become cold and numb. In addition, the body begins to shiver. Shivering warms the body as muscles contract rapidly. When this happens, some of the body’s potential energy is converted to kinetic energy, thus generating heat.

d. Ask students: What do you do when you become too hot? Student answers may vary. Students may try to find shelter or shade, take off extra clothing, jump in a pool or lake, or fan themselves.

e. Ask students: Can you think of any automatic responses of your body? Are there things your body does that you do not control when you are hot? Student answers may vary. Encourage students to realize that when they are too hot, their bodies perspire, or sweat.

f. Tell students that when their bodies become too hot, they begin to perspire. Explain to students that during the lab experiments, they will determine why the body perspires when it becomes overly warm.

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C. Tell students that by performing their lab experiments, they will begin to answer the following questions:

Why does the body perspire when it is overly warm?

Can we change the temperature of the air exhaled from our bodies?