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

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A. Begin this Investigation by directing students to locate their Physical Fitness Log from the end of their Student Data Record.  Ask students to organize into their exercise pairs.

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

2. Each student should perform their exercise, either the leg lift for 1.5 minutes for each leg, or jumping rope for four minutes.

3. After students have completed their exercises, they should immediately take and record their heart rates in their Physical Fitness Log.

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B. Begin analysis of the laboratory experiments by asking students to summarize what was done during the laboratory portion of the Investigation.  

Students should indicate that the laboratory experiments focused on energy balance and determining the relationship between energy input and output.  They created a model of energy balance by using a lever.  One side represented energy input, the other energy output.  

Students then determined the energy balance of two boys, Keith and Tim, by comparing their diet, basal metabolic rate, and activities they performed during one day.

1. Ask students:  How would you describe Keith and Tim’s energy balance? Why? When Tim or Keith performed Set B activities, their energy input was greater than their energy output.  The same was true even when Keith performed Set A activities.  However, Tim was able to balance his energy input and output when he performed the activities in Set A.

2. Why do you think Tim was able to balance his energy input and Keith was not? Student answers will vary.

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C. To help students further investigate the reasons for the difference between Tim and Keith’s energy balance, direct students to rejoin their five lab groups.  They will use the following exercise to evaluate the menus for nutritional content.  The goal of this exercise is to encourage students to think about how food choices influence energy balance.

1. Direct students’ attention to Menus 1 and 2 from Problems 2b and 2c in their Student Data Record.  Remind students that these menus were used in Trial 1 to determine Tim and Keith’s energy input for Trials 2-5.

2. Assign a meal to each group for analysis, and direct students to indicate their group’s meal assignment in Problem 8a of the Student Data Record.

3. Direct students to calculate energy input consumed during each part of the menu and place their answers in the Table provided in Problem 8b.

4. Draw the following Table on the board and direct one student from each group to supply the values for the group’s meal to complete the Table:

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5. Direct students’ attention again to the menus, and instruct the groups to evaluate the menus in terms of the boys’ food choices.  Encourage students to refer to the MyPlate graphic in the Student Data Record as necessary. Students should use their observations to answer Problems 8c-8d in their Student Data Record.

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6. The Trials in this Investigation examined energy balance on the basis of total daily energy input and total daily energy output.  However, in real life, the body does not wait until all the energy is consumed for the day before subtracting the energy used for that day. Instead, people alternate between consuming food and performing activities throughout the day, which means that energy balance fluctuates as the day progresses.  Use the following questions to encourage students to think about how someone can arrange his or her energy input to better suit the body’s energy output throughout the day:

a. Direct students to study the chart on the board.  

Ask students:  Which meals were close in energy values between menus? The morning meal and midday meal.

b. Ask students: Which meals were very different in energy values between menus? The afternoon snack, evening meal, and bedtime snack.

c. Ask students: What can we predict about each boy’s ability to use the energy from the last two meals of the day before going to bed? Keith’s evening meals contained nearly double the amount of energy contained in Tim’s meals.  This means Keith was getting over half of his energy during the last hours of the day and would be unable to use much of the energy he consumes before going to bed, making it harder to balance his energy input and energy output for the day.

D. Before continuing further, pause and ask the class to reflect on their analysis thus far.

1. Ask students:  What question were we trying to answer? What conclusions can you make about how Tim and Keith’s food choices affected their energy input?

2. Ask students: What have we found thus far?  We have found that Keith’s food choices gave him a much higher energy input than Tim’s food choices.

3. Ask students: What other factor do we need to consider in energy balance? Energy output must be considered in energy balance.

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4. Remind students that in Trial 3 they evaluated how normal school day activities affected Tim and Keith’s energy balance.

a. Direct students to review Problems 4f-4g in the Student Data Record.

b. Remind students that the total energy output for the day included the energy expended during the school day as well as the energy expended during the after-school activity set.  Direct students to use this information to complete Problem 9 in their Student Data Record (Table in blue on this slide).

c. Use the following question to encourage students to draw a conclusion about their own energy output during a school day from the results of Trial 3.  

Ask students:  What can the results of Trial 3 tell you about the amount of energy Keith and Tim use during the school day? Students should conclude that the energy output during the school day for both Keith and Tim was less than the energy input.

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5. Remind students that in Trials 4-5 they evaluated the energy output of two different sets of activities through mathematical calculations and experimentation, and compared their results using a table and observations.

a. Direct students to determine the total amount of energy output for the day for both Keith and Tim.

b. Explain to students that scientists often use bar graphs to compare data for the purpose of drawing conclusions and presenting their results to other scientists.

c. Direct students’ attention to Problem 10a in the Student Data Record.  Instruct students to create a bar graph comparing Tim’s total energy input and output to Keith’s total energy input and output. Provide approximately 20 minutes for students to complete this portion of the PostLab exercise.  Students may wish to refer to their Procedural Toolbox for help in constructing their graphs.  One example of a graph is shown in this slide.

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6. Once student groups have completed their graphs, encourage several groups to draw their graphs on the board.  Direct students to study their graphs.  Pose the question: 

Ask students: Based on your results, who had a better energy balance—Tim or Keith? Does your graph demonstrate this?  How? Tim had a better energy balance.  The graph shows less difference between Tim’s energy input and energy output than between Keith’s energy input and energy output.

7. Direct students to write their answers in Problem 10b of the Student Data Record.

8. Ask students:  What do you notice about the MyPlate Graphic on your Student Data Record?  Does it only include information about food choices? Students should indicate that in addition to recommending amounts of foods in each food group or category, MyPlate also includes a logo of a person exercising or performing physical activities.

9. Ask students:  Think about what you learned in this Investigation about energy input, energy output, and energy balance.  Why do you think the MyPlate Graphic includes an activity logo? Students should indicate that a healthy body is one that is in energy balance.  Energy balance includes both energy input and energy output.  The goal of the MyPlate Graphic is to help people have healthy bodies and lead healthy lives.  Therefore, it includes information about energy input as recommended amounts of foods in each food group or category and information about energy output as a logo of a person involved in physical activity.  The logo of exercising serves as a reminder that a healthy body and healthy life include physical activity.

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10. Conclude the PostLab analysis by using the following questions to encourage students to think about the relationships between energy input, energy output, energy balance, and food choices:

a. Ask students: What is energy balance? Energy balance is the difference between energy input and energy output.

b.  Ask students: What factors influence energy input? The types and amounts of food consumed.

c. Ask students: What factors influence energy output? Basal metabolic rate and the amount and types of activity performed.

d. Ask students: What would happen if energy input was greater than energy output? Our body stores a large portion of what it cannot use immediately.  Some vitamins and minerals cannot be stored, but excess proteins, carbohydrates, and fats are stored as fat in fat tissue.  This may be fine for the short term but is unhealthy over the long term because it can lead to obesity and health problems.

e. Ask students: What would happen if energy output was greater than energy input? Our bodies would not have enough energy to repair and build cells and function properly and would have to use stored energy.  When this happens over a very long period of time, energy stores are used up and the body begins to break down its tissues and organs.

f. Ask students: What recommendations would you make to Keith to help him balance his energy input and output? Keith should decrease his intake of sweets and foods high in fat, carbohydrates, and total energy.  He should replace them with foods lower in fat, carbohydrates, and total energy.  He should also perform more moderate and vigorous activities during the day.

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11. Pose the following question, and direct students to write the answer in Problem 11 of the Student Data Record:  

Ask students: Look at Activity Sets A and B.  What conclusions can you draw about how to increase energy output in Set B?  The best way to increase energy output is to replace low-energy activities with moderate or vigorous activities.  It is also good to vary activity levels during the day and perform activities that require moderate or vigorous energy output for longer periods of time.