Assessment:
Consider asking students to describe the energy balance equation in their own words. This will stimulate thinking about the topic and give you an opportunity to assess informally students’ understanding of key concepts from Lessons 1 and 2.

1. Tell students they will explore the energy balance equation introduced at the end of Lesson 2.
2. Organize students into 10 teams and distribute one copy of Master 3.1, The Memo, to each team. Tell students to read the memo. Alternatively, show the transparency of the memo and read it with the class.

The memo sets up the scenario. Students play staff scientists at an energy balance clinic directed by a physician who specializes in energy balance issues. This physician, Dr. Chu, has delayed his return from a conference. The students’ task is to analyze the energy balance state of a fictitious patient (a middle school student) of the physician and to make recommendations about the patient’s energy-input and energy-output levels to the clinic’s review board. Student teams will learn about their patient when you distribute the patient files.

3. Assign one of the five patients from the energy balance clinic to each team and give each team the appropriate patient file (Master 3.5, Ashley’s Patient File; 3.6, Emily’s Patient File; 3.7, Enrique’s Patient File; 3.8, Jerome’s Patient File; or 3.9, Kim’s Patient File). Give each team a copy of Master 3.10, Energy Balance Reference Manual.

Assign two teams to each of the five fictitious characters.

4. Explain that the students’ first task is to evaluate the patient’s concern. The following information is available to them:

• a patient file, which contains a statement of the patient’s concern;
• a typical one-day food diary for the patient;
• a typical one-day physical activity diary for the patient; and
• an energy balance reference manual.

5. Ask students to look at their copy of the energy balance reference manual. Point out the topics covered in the manual. Stress that the manual contains valuable information students need to complete their tasks.

The reference manual contains information students will need: the number of calories per gram of protein, carbohydrate, and fat; the calories used per hour for activities at each of five intensity levels; the energy balance equation; information about energy balance in adolescents and teenagers; and information about normal weight gains in middle school–aged males and females.

Tip from the field test: Reviewing the reference manual with students at this time is important; otherwise, they tend not to consult it for the information they need to complete the activity.

6. Tell students to begin by reading the first section of their character’s patient file. This contains the patient’s concern expressed as a question, followed by a short explanation.

This information sets the stage for the students’ work. For example, Ashley asks, “Am I going to get fat?” Student teams should begin by determining the energy balance state of their patient. Students should consult their reference manual to aid in their evaluation.

7. Ask students to describe how they can evaluate their patient’s energy balance.

Students need to calculate Energy_in from the one-day food diary and Energy_out from the one-day physical activity diary.

Content Standard A:
Develop descriptions, explanations, predictions, and models using evidence.

8. Tell students to proceed with the calculations to determine their patient’s energy balance. Provide each student with a copy of Master 3.2, Calculating Energy_in and Energy_out, which will aid students in performing their calculations.

Allow students 20 to 30 minutes to complete this part of the activity. Students use the information in the files to calculate the total calories their patient consumes. They must first calculate the total grams each of fat, carbohydrate, and protein consumed by their patient in the day represented by the diary. The calories-per-gram factors for fat, carbohydrate, and protein are found in the reference manual. Similarly, students calculate the total hours spent engaging in physical activities at each intensity level. Using the calories-per-hour factors provided in the reference manual, students can calculate the total calories the patient uses in physical activity.

Tip from the field test: Point out to students that the food diary provides the total grams of protein, carbohydrate, and fat by meal in boldface. These numbers are provided as “subtotals” for each meal and snack. Students should add only the boldface numbers, not the grams for each food within each meal and snack.

Teacher note: Move among the teams as they complete their analyses to answer any questions that arise. Ask questions such as, “Why was your patient asked to provide information about food consumption and physical activity for a typical day, rather than exactly what they ate and what activities they performed on only one specific day?” Emphasize that energy balance is evaluated over the long term (weeks and months) rather than over a single day.

This point is made in the reference manual. Similarly, weight gain or loss is determined by the balance of Energy_in and Energy_out over the long term, rather than on any single day.

Teacher note: We realize that children should not be consuming alcohol-containing beverages. However, should students ask, alcohol alone contributes 7 calories per gram and no nutrients. There are concerns about alcohol intake among adolescents. Consumption of alcohol-containing products may upset both energy balance and nutritional status in addition to having other adverse effects on adolescent health and safety. Understanding Alcohol: Investigations into Biology and Behavior is a unit in the NIH curriculum supplement series that you will find useful for investigating this topic with your students.

9. When students have completed their calculations, give each team one copy of Master 3.11, Energy Balance Diagram, and one copy of Master 3.3, Patient Notes. Instruct teams to complete Master 3.11 for their patient and answer the questions on Master 3.3.

The students’ next task is to evaluate the patient’s concern and make recommendations regarding the patient’s energy intake and energy output. To complete the Energy Balance Diagram, students need to determine the number of pounds their patient gained or lost over the summer. This is done using the typical day’s calorie consumption and expenditure and the number of calories per pound of stored fat:

[(E_in – E_out) × 84 days in the summer] ÷ 3,500 calories per pound of stored fat = number of pounds lost or gained during the summer

For example, if a patient consistently consumed 100 more calories per day than he or she expended, the calculation is: [100 × 84] ÷ 3,500 = 2.4 pounds gained over the summer. In this case, students would tilt the balance so that it points upward to a point approximately midway between “Balance” and “+ 5” pounds, as follows:

The Patient Notes will help students prepare their presentations for the Energy Balance Review Board in Activity 2 of the lesson. Information that will help students evaluate normal weight gain for adolescents can be found in the reference manual.

Content Standard A:
Think critically and logically to make relationships between evidence and explanations.

10. Combine the two teams that evaluated the same patient and ask them to compare their analyses and resolve any discrepancies.

Discrepancies can arise from not selecting the correct numbers to add, from adding or multiplying incorrectly, or from not using the correct multiplication factor for activity level or for energy derived from protein, carbohydrate, and fat.

Activity 2: Evaluation and Recommendations

1. Reconvene the combined teams from Activity 1 and direct them to prepare a short report (about five minutes) to the Energy Balance Review Board regarding their patient’s energy balance and their recommendations to the patient.

Content Standard A:
Scientific explanations emphasize evidence, have logically consistent arguments, and use scientific principles, models, and theories.

The Energy Balance Review Board is the teacher and the rest of the class. Give each combined team a transparency and a transparency pen so they can prepare visual aids. On the transparency, students could include their patient’s question, their values for Energy_in and Energy_out, their scale graphic showing weight gain or loss, their recommendations for the patient, and anything else they deem relevant.

2. Direct students to prepare two or three questions they could ask the other teams about their analyses and recommendations for the other patients.

Give each team one copy of Master 3.4, Evaluating Energy Balance Review Board Presentations. The master includes the criteria that you will use to evaluate the students’ presentation and participation in the review board portion of the activity.

You may want to assign roles to each team member to ensure that all members participate. For example, three students could be spokespersons (one to describe energy output, one to describe energy input, and one to summarize the patient’s energy balance), one or two students could prepare the visual aids, and one or two students could write the script for the presentation. All team members should be prepared to answer questions from the review board.

3. Ask each combined team to present its report to the Energy Balance Review Board (the rest of the class) and allow three to four minutes for questions from the board.

Assessment:
For a formal assessment of student learning, assign points to each group’s presentation using the evaluation rubric.

Explain to students that the role of the review board is to evaluate the accuracy of the analysis and the appropriateness of the recommendations before the physician speaks with the patient.

Point out that the evaluation rubric for the presentations also includes a category for their participation as members of the review board.

4. Conclude the activity by conducting a brief class discussion. Ask, “Which of the five patients has a healthy energy balance state?”

Students should justify their answers. Ashley, Emily, and Jerome are in positive energy balance; that is, energy intake is greater than energy used and they are gaining weight. Students should have considered the issue of weight gain in adolescents (described in the energy balance reference manual) and concluded that Ashley’s weight gain is normal and healthy for a girl her age. On the other hand, Emily and Jerome may be gaining too much weight. Kim is in energy balance, a state that is not healthy for adolescents because of the extra energy required for growth and development. Enrique is in negative energy balance; that is, his energy intake is less than his energy output and he is losing weight. This, too, is not healthy, since he needs to consume more calories than he expends in order to have energy to meet the needs for growth.

Content Standard F:
Nutrition requirements vary with body weight, age, sex, activity, and body functioning.

5. Ask, “If the five patients were adults rather than middle school students, would your answer be the same?” Why or why not?

If the five patients were adults, achieving energy balance would be optimal; that is, over the long term, Energy_in and Energy_out would be equal. Kim is in this state. This is optimum for adults because they no longer need extra calories for growth and should strive to maintain a healthy weight. Recognizing this will prepare students for Lesson 5, in which they write a letter to their adult selves explaining the optimum energy balance they should strive for at that point in their lives.

Teacher note: This unit focuses on energy balance, and it deals specifically with caloric intake and expenditure. It does not raise issues nor provide guidance about specific food choices and the nutritional content of foods. Nonetheless, students may comment about the diets of the five fictitious characters. Jerome’s diet, for instance, contains no fruits or vegetables other than French fries. Enrique’s diet also contains fewer than the recommended servings of fruits and vegetables. Because this unit may increase student interest in the foods they consume as their Energy_in, you might point out that there are guidelines for the appropriate number of servings from the basic food groups (students are generally exposed to the Food Guide Pyramid in elementary school). For instance, the daily diets of adolescents should contain at least four servings of vegetables and three servings of fruit. This information may be found in Box 7 on page 14 of the pdf version of Dietary Guidelines for Americans, available online at http://www.health.gov/dietaryguidelines/.