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

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A. Begin the lesson by explaining to students that they will conduct one type of experiment over the course of the CELL.  They will complete a part of the experiment during each PreLab and each PostLab of the CELL.  The experiment will test the effect of training, or regular exercise, on cardiovascular and muscular fitness.

1. Ask students:  Do you recall the types of exercises you performed during the Lab? Students should recall that they either jumped rope or performed leg lifts.

2. Direct students’ attention to the Physical Fitness Log in the Student Data Record and explain that in the Lab they tested whether they could perform leg lifts for two minutes or rope jumping for five minutes.  This was done as a way for each student to determine their level of cardiovascular and muscular fitness.

3. Explain that today they will start a training program.

a. The training program is designed so that during each Investigation they perform the same exercises as in the Lab (leg lifts or rope jumping) for longer periods of time.

b. Today they will start with leg lifts for 30 seconds and rope jumping for one minute.  At the end of the CELL, they will determine the effect of this training on their level of cardiovascular and muscular fitness.  Tell students to review their Physical Fitness Log.  Direct them to pay special attention to the periods during which they will perform their exercises and note the increases in the duration of the exercises over the course of the CELL.

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4. Tell students to organize into the same pairs they had when performing their exercises in the Lab.

5. Direct students to follow the same procedure to complete their exercises with the same student in each pair performing the same exercise.  For example, if Peter did the leg lifts and Sara did the rope jumping exercises during the Lab, Peter should continue to perform the leg lifts throughout the CELL and Sara should continue to perform the rope jumping exercise.

6. Students should first take and record their resting heart rates in the appropriate column of the Physical Fitness Log before beginning their exercises.

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7. Each student should perform their exercises, either the leg lifts for each leg for 30 seconds or jump rope for one minute.

8. After students have completed their exercise, they should immediately take and record their heart rates in the appropriate column of the Physical Fitness Log.

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B. Begin the analysis of the Investigation by asking students to summarize the experiments they conducted in Lab and the purpose of those experiments. The questions that follow may be helpful in prompting student discussion.

1. Ask students: Do you recall the two systems investigated during the Lab experiments?  What were they? The cardiovascular system and the respiratory system.

2. Ask students: Can you summarize the types of experiments that you performed as you investigated these systems? Students observed what occurs while inhaling and exhaling, used the spring scale as a model to represent the process of respiration, determined how to locate their pulse, measured their heart rate, and evaluated their level of cardiovascular fitness after jumping rope and performing leg lifts.

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C. Ask students to think about their experiments and how the cardiovascular system and the respiratory system work together to get blood and oxygen to all the parts of the body.

Guide students in using the Cognitive Tool called Mind Movie to imagine seeing the blood flow through the body. 

1. Tell students to sit back in their chair, close their eyes, and relax.

2. Ask them to use their imagination to create a detailed movie in their minds of how the blood flows through the heart and lungs and to the rest of the body.

3. Remind students they can play their movie over again to help visualize blood flow.

4. After providing students several minutes to imagine their movie, ask for a volunteer to share what they saw in their Mind Movie and describe the flow of blood through the body.

Oxygenated blood leaves the heart and moves through arteries, then capillaries, to the cells and organs of the body where oxygen is exchanged for carbon dioxide.  The deoxygenated blood flows back to the heart through capillaries, then veins.  The blood enters the heart and is pumped to the lungs where carbon dioxide is exchanged for oxygen.  The oxygenated blood flows back to the heart where it is pumped out and the process repeats again.

5. Ask students:  Based on how blood flows through the body, can you describe the main functions of the cardiovascular and respiratory systems? The main function of the respiratory system is to provide oxygen to the cardiovascular system and rid the cardiovascular system of carbon dioxide.  The main function of the cardiovascular system is to provide the body with oxygen and nutrients and to collect the waste products from the organs and structures of the body.

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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.

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D. Continue the analysis of the cardiovascular system by posing the following questions.

1. Ask students: How did you determine your cardiovascular system was working? Students could see arteries and veins, two types of structures of their cardiovascular system on the body.  They could also determine that the cardiovascular system was pumping and circulating blood by measuring their heart rate with a stethoscope and by feeling their pulse.

2. Ask students: What differences did you notice when measuring your heart rate using your pulse versus the stethoscope? When calculating heart rate from a pulse, each heartbeat was felt as a sensation of blood pushing against the skin.  Each push or pulse was counted as one heartbeat. When using a stethoscope, the heartbeat was heard as a series of two sounds.  Each series of two sounds was counted as one heartbeat.

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a. To help students visualize what causes the difference between the sounds they heard and the sensation they felt, direct students to place the palm of their hand over the left side of the chest and take a moment to feel their heart beating.  

Ask students: What do you feel and why do you feel it? Students should feel a very slight movement against their hand as the left and right ventricles contract or squeeze tight.  As the ventricles contract, they push the blood from the heart through the arteries and veins in the body.  In between each contraction, the ventricles relax.

b. Ask students: How does the feeling of the movement of the heart in the chest relate to what you hear when using a stethoscope? Students hear both the contraction and relaxation of the heart.

c. Ask students to close their eyes and think about what they heard when they listened to the heart with their stethoscope.  

Ask students: Can you describe what the heart sounds like when you listen to it with the stethoscope? It makes a “lub-dub” sound.

d. Ask students: Why does the heart make this sound? The “lub” sound occurs when the right and left ventricles contract or pump the blood. The “dub” sound occurs when the ventricles relax.  At this point, blood is flowing back into the ventricles from the atria, the two top chambers of the heart.  The “lub-dub” sound is equal to one full beat of the heart.

e. To ensure that students are associating the contraction and relaxation of the ventricles with the “lub-dub” sound, mimic the motion of the ventricles with your hands.

• Cup hands close together to simulate the ventricles contracting and say “lub.”
• Move hands so they are apart to simulate the heart filling with blood as the ventricles relax and expand and say “dub.”
• Repeat this motion with the words several times.

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E. Discuss how students determined their heart rate using either their pulse or the stethoscope.

1. Ask students: Can anyone describe the type of calculations you used to determine your heart rate? Students were encouraged to determine the number of heartbeats in a 10 second period and then multiply that number by six to determine the heart rate.

2. Ask students to share their resting heart rates; those they took when sitting down. Record ten to fifteen of the heart rates on the board.  Sample data could include 72 beats/min, 80 beats/min, 64 beats/min, 70 beats/min, 75 beats/min, etc.

a. Ask students:  Did everyone have the same heart rate? No. Students should notice some variation between the reported rates.

b. Ask students: What did you notice about the values for the heart rate? Students should notice that although the values are not the same, they are similar.

c. Ask students: Have you ever heard anyone refer to a normal range for heart rate?  What do you think that term means?  Can your data help you to answer the question?  

Biologic variation, or small differences, in organisms is normal.  One of the places biological variation exists is in the heart rate.  A small variation in a person’s heart and cardiovascular system often means that their heart rate is slightly different from someone else’s heart rate.  

However, the variations are small enough that the heartbeats of people fall within a certain range.  For children ten and over, the normal range is 60 to 100 beats per minute.  Students should observe a range of heart rates within their class that falls within this normal range, illustrating this point.

3. Ask students: Compare your heart rate from before and after you performed your exercises.  What happened to your heart rate after you exercised? The heart rate increased after exercise.

4. Ask students: How did you feel after exercising – performing the leg lifts and jump rope activities?  Did you notice any other changes in your body as you were exercising or after you exercised?  How might this relate to your level of cardiovascular and muscular fitness? Student answers will vary.  

Some students may have been too fatigued and short of breath to continue exercising the entire time period.  Some students may have completed the exercises with a slight shortness of breath, and other students were somewhere in between these two points.  The ease or difficulty students experienced when performing their exercise is an indication of their level of physical fitness.

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F.  To complete this Investigation, tell students they will continue to study the additional effects that exercise has on their bodies in the next Investigation.  Questions they will explore will include:

Does regular exercise affect how much blood can be pumped with each heartbeat?

Can regular exercise change a person’s resting heart rate?