Activity 7 – What is a balanced diet?

Through mathematics and technology integration, students will understand what it means to have a balanced diet, as well as explore the causes and effects of healthy and unhealthy eating habits.

Learning outcomes

Students will:

• Assess their diets and determine whether their calorie equation is in balance
• Evaluate meals and snacks that based on the principles of My Pyramid
• Understand the concept and the benefits of eating in moderation
• Understand the relationship between physical activity and nutrition
• Solve problems by using calculators and computers
• Solve problems by comparing two sets of related data
• Identify, describe, and generalize relationships in which quantities change proportionally
• Identify, describe, and generalize relationships in which change in one quantity relates to change in a second quantity

Teacher planning

Time required

1 day (2 class periods, math and science) or 2 days, 60 minutes each day

Materials needed

• Pan balance (1 per group)
• 2 sets of metric weights per group (minimum recommended: four 50-gram weights, three 100-gram weights, and three 200-gram weights and one each of 500—gram and 1000—gram weights for a total weight of 2,600 grams)
• Supply of centimeter cubes
• Calculators
• Chart paper
• Markers

Student handouts

Technology resources

Laptop computers, at least 1 per group

Pre-activities

• A week before the activity, have students record their diets and exercise on the data sheet. Students will use their own diets for this activity. Have students log foods and food amounts into the data sheet. This can be done as a homework assignment.
• Each group will need a laptop, one pan balance, two sets of metric weights, a supply of centimeter cubes, calculators, and data sheets. They will also need their MyPyramid plans from the lesson How Much Am I Supposed to Eat?
• Students should be grouped in minimums of two.

Activities

1. Begin by reviewing the information learned about nutrition during all previous activities, especially from the lesson How Much Am I Supposed to Eat?
2. Ask students to remind you what the purpose of food is (to provide energy and nutrients). Then, ask them, “How do we know how much energy and nutrients we need?” Some students might say the My Pyramid plan or the government; ask, “How do they know?”
3. Have students write the question of the day and make predictions to both questions. Discuss predictions.
4. Ask, “What is a calorie?” (A measure of potential energy in food.) Say, “If people eat calories, what do they do with them?” Accept all appropriate answers and lead students to understand that they are expended with activities — everything the body does needs energy. So we measure the energy people use with calories as well.
5. Ask, “Does anyone know how many calories you need to per day to just sit around and do nothing?” Let students guess and then tell them it’s based on their weight (body weight × 10). If students know their body weight, let them calculate their Resting Metabolic Rate (RMR), or what their body needs to just live. For example, an 130-pound woman would need 1,300 calories a day to just live.
6. Ask students to then guess how many calories they need to do what they do and live.
7. Have students retrieve the My Pyramid plan from the lesson How Much Am I Supposed to Eat? Tell students that researchers and scientists came up with the My Pyramid plan by looking at what the average person does. But that your activities dictate how much you need to eat. If you are not very active, you don’t need to eat as much (about 20–40 percent of your RMR). If you are moderately active, you can eat a bit more (about 40–60 percent of your RMR) and if you are very active, you can eat even more (about 60–80 percent of your RMR). You can eat more because you are using more.
8. Give students Card 1 and tell them that you will do this one all together, step-by-step. Read, “Steven has been told by a dietitian that he needs to eat 2,400 calories a day.” Have students put this on one side of the balance using the weights. Tell students the balance represents Steven and what they’ve put on there is what he needs to grow and go.
9. Record on the board or chart paper: 2,400 =
10. Then, read over Steven’s food journal. Have students model the calorie amounts using the weights and add them to the other side of the balance, while you record in standard form on the board, completing the equation.
11. Ask, “Is the equation balanced?” No. “What happened? Steven did not eat enough. So what does that mean for Steven? What does he need to do?” Record responses as causes and effects on chart paper. Students should understand that Steven would lose weight.
12. Have students complete Card 2 while you facilitate.
13. When just about all students have finished, ask again, “Is the equation balanced?” No. “What happened?” Mikayla ate too much. “So what does that mean for her? What does she need to do?” Record responses as causes and effects on chart paper. Students should understand that Mikayla would gain weight. Take time to review and reinforce algebraic concepts.
14. Students complete Card 3.
15. When just about all students have finished, ask again, “Is the equation balanced?” Yes. “What happened?” Keisha ate just enough. “So what does that mean for her?” What does she need to do? Record responses as causes and effects on chart paper. Students should understand that Keisha would maintain her weight. Take time to review and reinforce algebraic concepts.
16. Ask, “What does Steven need to do to balance his equation? What about Mikayla? How does Keisha maintain her equation balanced?”
17. Have students reflect on what this means for them.(Good place to stop if using 2-day option.)
18. Now, have students use the laptops and online calorie calculators listed in the Learn More section to determine the number of calories they consumed in one day of their food journal and record them on their data sheet.
19. Next, students should carry out the same balancing equations procedure to analyze their own eating habits and work on the Balancing My Equation worksheet.
20. They may repeat the procedure for several days or the entire week in order to determine and analyze trends in the data.
21. Students should understand that diets are sometimes a numbers game and the implications thereof.
22. Ask, “What do you need to do for your equation?”
23. Have students reflect on what this means for them.
24. Finally, direct students to all essential questions and the QOD.
25. Have a short closing discussion to review essential understandings for this activity and add student ideas to the charts.

Assessment

• Students should record an answer to the QOD in their science notebooks that correctly applies essential understandings of the activity.
• Take note of student responses during Card Activities.
• Assess the Balancing My Equation worksheet.

Modifications

• Students can complete portions of the Balancing My Equation student sheet.
• Students may complete card activities independently as a center activity.
• There are a plethora of calorie counting books that can be used in place or as a complement to online food calorie calculators.
• Online balances may be used if pan balances are not available or limited.

Supplemental information

Watch for students misunderstandings that in order to lose weight, you only need to eat less; in order to gain weight, you only need to eat more; in order to maintain weight, you only need to equal your caloric output and your input. Remind them it’s also about what you eat and your activity level.

Critical vocabulary

• Calories
• energy
• Resting Metabolic Rate
• dietitian
• balance
• equal/equivalent
• represent
• equation
• analyze