This is the first Investigation of the LabLearner CELL Examining Exercise.

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A. Begin the CELL by performing an activity that will prompt students to recall what they know about physical fitness and illustrate their ideas about what constitutes physical fitness and health.  

Ask students:  What are five things that you think make a person an Olympic athlete?

1. Tell students to think about this question and recall what they know about physical fitness and health.  Direct students to record their answers in Problem 1 of their Student Data Record.  Allow several minutes for this activity.

2. Ask students:  If you wanted to be an Olympic athlete, what do you think would help you attain this goal?

3. Tell students you will read ten statements.  As you read the statements, they should determine which statements they think would help them to become an Olympic athlete. Direct students to the statements listed in Problem 2 of their Student Data Record. Ask students to follow along as you read the statements.  Students should then place a check in each box they think would help them to reach this goal.

4. Ask students:  Why do you think what you checked would increase your chances of becoming an Olympic athlete? Student answers will vary.

5. Discuss student answers and their concepts of physiological traits associated with Olympic athletes as a way of assessing students’ previous knowledge of physical fitness and familiarity with the concepts.  Avoid indicating whether their ideas are correct or incorrect, as students will determine the answers to this question as they perform each Investigation in the CELL.

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B. Describe the focus of this CELL to students:

1. This CELL is designed to help students make informed decisions to increase their level of physical fitness.  The Investigations will explore the cardiovascular, respiratory, and musculoskeletal systems and how they relate to the benefits of regular exercise and a healthy diet.

2. Tell students that after they conclude their investigations they will be asked to answer a similar survey about athletes and can compare whether their original ideas about physical fitness have changed.

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C. Explain to students that to understand how exercise relates to changing their physical fitness, they will need to understand how blood circulates through the body. Ask students to refer to their Scientist’s Glossary as the terms are used in your discussion.

Initiate a discussion about the heart.  Ask students:  What do you know about the cardiovascular system and the heart?  Use the following points during your discussion:

a. The heart is the size of a fist.

b. The heart is one of the strongest muscles of the body.

c. The heart constantly pumps blood throughout the body.

d. The arteries carry blood from the heart to the organs and other areas of the body.

e. The veins carry blood from the organs and other areas of the body back to the heart.

f. The heart slows during times of rest and sleep.

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3. Direct students to locate the diagram of the heart and lungs in Problem 3 of their Student Data Record and to reference their Scientist’s Glossary.

4. Before beginning, ask students:  Does the diagram represent how the heart and lungs are located in your chest? Student answers may vary. The diagram is a mirror image of how the heart and lungs are located within students’ chests.  Therefore, the left side of the diagram represents the right side of the chest and the right side of the diagram represents the left side of the chest.

5. If necessary, direct the students to hold the diagram in front of their chests and look down to observe how the organs in the diagram are situated (see slide).  Point out that the heart is on the left side of their chest.

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6. Discuss the flow of blood as it moves through the heart and lungs.  The flow of blood through the body is a closed-circuit or circle and, therefore, can be described from many starting points.  The steps below begin on the left side of the heart.

a. The heart pumps the blood from the lower chamber on the left side of the heart.  The chamber is called the left ventricle.  From the left ventricle, blood is pumped into the aorta, the main artery that leaves the heart.  This blood is rich in oxygen.

b. The blood flows from the aorta through smaller arteries, which eventually lead to tiny capillaries.

c. The oxygen and nutrients in the blood move through the thin walls of the capillaries into the cells and organs of the body.

d. Carbon dioxide and waste products move from the cells and organs of the body through the capillary walls into the blood located in the capillaries.

e. The blood flows from the tiny capillaries into the larger veins.  This blood contains very little oxygen and a relatively large amount of carbon dioxide.

f. This oxygen-poor blood flows from the veins into the right atrium of the heart.  The right atrium is the top chamber on the right side of the heart.

g. The blood moves from the right atrium through the tricuspid valve into the right ventricle or lower right chamber.

h. From the right ventricle, blood flows through the right and left pulmonary arteries into the right and left lungs.

i. In the lungs, oxygen is transferred from the lungs into the blood and carbon dioxide from the blood into the lungs.  This transfer occurs at the level of the alveoli of the lungs and capillaries surrounding the alveoli.  The alveoli are tiny air sacs in the lungs.

j. The blood flows from the right and left lungs through the pulmonary veins to the left atrium of the heart.  

k. From the left atrium, blood flows through the mitral valve into the left ventricle, where the entire process begins again.

7. Review the circulation pattern again, encouraging students to rehearse the pathway by tracing the movement of blood through the heart and lungs, using the diagram in Problem 3 of their Student Data Record.

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D. Explain that in the first Investigation, students will study blood flow and the cardiovascular system.  As a part of the Investigation, they will determine their heart rate.  Therefore, students may find it beneficial to review what is meant by the term rate.

1. Ask students: What is meant by the term rate? Student answers will vary. 

2. Refer to the definition of the term rate on the slide.

3. Refer students to the term heart rate in their Scientist’s Glossary and/or at the bottom of the slide. 

Ask students:  How does the definition for rate compare to the definition for heart rate in your Scientist’s Glossary? Student answers will vary.

4. Refer to the definition for heart rate on the slide (the measure of how many times the heart beats in one minute).  

Compare the quantity in the definition for the term rate with the quantity in the definition for the term heart rate.  

Ask students:  What is the event or quantity that is being measured in a heart rate? The number of times the heart beats.

5. Ask students:  Based on your understanding of heart rate, how would you measure heart rate?  The number of heartbeats would be counted over a time period of one minute.

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6. Tell students that they will be taking their heart rates during the experiment.

a. Review the Procedural Tool for determining a heart rate with students.  Students may wish to refer to their Procedural Toolbox, Calculation of Heart Rate, as you review the steps.

• • • Determine the time period during which you will count the heartbeats.  This may be one minute, 30 seconds, 15 seconds, 10 seconds, or even 6 seconds.
    • Assuming the 10 second interval was chosen, count the number of times the heart beats in the 10 second period.
    • To determine the number of beats per minute, multiply the number of beats by six because there are six 10 second increments in one minute.  If the 30 second time period were chosen, the number would be multiplied by two.

Heart beats / 10 seconds × 6 = heartbeats / minute = heart rate

For example, 10 beats / 10 seconds × 6 = 60 beats / minute

b. Allow students several minutes to practice calculating heart rate by providing several examples on the board:

12 heartbeats / 10 seconds = 72 beats / minute 

15 heartbeats / 10 seconds = 90 beats / minute 

20 heartbeats / 10 seconds = 120 beats / minute

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E. Tell students they will conduct experiments in this Investigation that will enhance their understanding of the cardiovascular and respiratory systems and how they relate to exercise.

a. As they conduct their experiments, they should think about the following questions:

How does blood move through my body?

What happens to my body when I exercise?

b. Tell students that they will be able to answer these questions using information from their experiments.