In this third Investigation of the LabLearner CELL Exploring Nutrition, students will continue their study of nutrition by focusing on carbohydrates. 

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A. Begin the Investigation by reviewing some of the concepts students have studied thus far in this Core Experience.  Initiate a discussion by asking students the questions that follow.

1. Ask students: What are two resources that you can use to choose nutritious foods? Students should indicate that they can use MyPlate and the nutrition labels on food items to help them choose nutritious foods.

2. Ask students: What are the food groups and categories found in MyPlate? Students should suggest that the six food groups are (1) the grains group, (2) the vegetables group, (3) the fruits group, (4) the dairy group, (5) the protein group, and the (6) oils group.  The categories are the limited foods.

3. Ask students: What other information is provided by MyPlate? Students should indicate that the recommended daily amount of food from each food group is also included.

4. Ask students: Why is it important to provide your body with the proper nutrients? Students should indicate that it is important to provide their bodies with a balanced selection of nutrients to have the energy to function and to stay healthy.

5. Ask students: How does the %DV help you to choose foods that will provide a healthy balance of nutrients? Students should indicate that the %DV helps them to compare the nutrient content of different foods and apply that toward the daily total they are eating.  For example, they can compare different brands of the same food product to see which has the range of nutrients they need.  If they eat a favorite food item that is high in a certain nutrient, they can balance that food with foods that are low in that nutrient for the rest of the day.

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B. Explain to students that in Investigation Three they will learn more about one of the types of nutrients listed on nutrition labels, carbohydrates.  Ask students to locate their Scientist’s Glossary.

1. Ask students:  What is a carbohydrate?  Have you heard this term before? Student answers may vary.  Students should have noticed the term on the nutrition label in the previous Investigation.

2. Direct students to look at the definition for the term carbohydrate.  Explain that carbohydrates are one of the nutrients found in food and used by the body.  There are different types of carbohydrates including sugars, starches, and dietary fiber. 

3. Explain to students that one of the main functions of carbohydrates is to supply the body with energy. When most carbohydrates are consumed, they are mechanically and chemically digested into a nutrient called glucose, which is absorbed into the blood.

4. Direct students to read the definition for the term glucose.

“Glucose:  One of the simplest forms of a sugar (carbohydrate).  Almost all of the carbohydrates ingested are broken down through the process of digestion and metabolism into glucose.  Glucose is carried by the blood to cells and used as the primary source of energy by the body. Glucose also occurs naturally in fruits and honey.”

5. Ask students:  In what part of the digestive system are most of the nutrients absorbed and transported to the body? Students should indicate that most of the absorption of nutrients occurs in the small intestine. 

Note to Teacher: Some absorption of nutrients occurs within other organs of the digestive system such as the stomach. However, it is not expected that students will or should recognize this concept at this time.

6. Ask students:  How do you think glucose is able to move from the digestive system to other organs where it is needed? Students should indicate that the glucose is carried by the blood to the cells of the body where it is used for energy.

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C. Explain to students that they will continue reading the short play about Jason and Dr. Greene. It will help them better understand the role of carbohydrates in nutrition.  Divide the students into pairs and encourage them to take on the roles of the characters in the story: Jason and Dr. Greene.

1. Ask students to locate problem 1 of their Scientist Data Record.  Set the scene for the students by explaining that Jason has brought some nutrition labels to Dr. Green’s office so he can understand how to properly balance the nutrients in the foods he eats.  Dr. Greene then reminds Jason that it is important to eat foods that will provide his body with a balanced supply of nutrients.

2. Students will read:

Jason:  Where on the nutrition label can I find how many carbohydrates I’m eating? 

Dr. Greene:  Look in the part that lists Total Carbohydrates.  This tells you how much of all of the different kinds of carbohydrates the food contains.

But there is also other information about different kinds of carbohydrates on the label.  A nutrition label also tells you how much dietary fiber and sugars are in the food. Remember dietary fiber and sugars are two kinds of carbohydrates.

Because there are many other kinds of carbohydrates, some nutrition labels include a section called Other Carbohydrates.

Jason:  What is a carbohydrate?

Dr. Greene:  Carbohydrates are found in many foods.  There are different types of carbohydrates such as sugars, starches, and dietary fiber.  Some foods, like fruits and vegetables, contain sugar.  Other times sugar is added to foods, like the sugar in soda, cake, and a cookie.  The sugars contained in food can have many different names, such as fructose, glucose, lactose, maltose, or sucrose.  These names can be found on the ingredient list on food packaging.  Some foods, like bread and rice, contain starch. Another type of carbohydrate is dietary fiber.  Dietary fiber is found in foods such as whole grains, fruits, and vegetables.

Jason:  After I eat a food that contains carbohydrates, what happens?

Dr. Greene:  Your body breaks down the sugars and starches you eat into a type of sugar called glucose.  Glucose is carried by the blood to organs in your body and used for energy.  If your body doesn’t need all the glucose right away, it stores glucose for later use as a carbohydrate called glycogen or as fat.  Most of the fiber you eat cannot be digested.  It passes through the digestive system.

Jason:  If fiber just passes through my digestive system, why does my body need it? 

Dr. Greene:  Fiber is good because it helps to move undigested food through your small and large intestines. 

Jason:  Can I eat too much sugar? 

Dr. Greene:  Yes, you can eat too much sugar.  Too much sugar can cause problems like tooth decay, heart disease, diabetes, and obesity. 

Jason:  Is there anything else that I should do? 

Dr. Greene:  Yes, remember to drink lots of water.  Water is an important nutrient that helps to move food through your digestive system.  It also helps to keep the body functioning properly. 

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3. As student groups reach this portion of the play, encourage them to return to their seats and reflect on what they have learned from the play.  The following questions may be useful in directing the class discussion:

a. Ask students: What nutrient did Jason and Dr. Greene talk about? Students should indicate that they talked about carbohydrates.

b. Ask students: Is there one type of carbohydrate or several types of carbohydrates? Students should indicate that there are many types of carbohydrates such as sugars, starches, and dietary fiber.

c. Ask students: What is one of the main functions of carbohydrates in the body? Students should indicate that carbohydrates are broken down into glucose by the body and used for energy.

d. Ask students: What type of carbohydrates do the cells and organs of the body use for energy? Students should indicate that sugars and starches are broken down into glucose and used for energy.

e. Ask students: Can all carbohydrates be broken down into glucose? Students should indicate that most dietary fiber, which is a type of carbohydrate, can not be broken down into glucose.

D. Tell students they will conduct an experiment in this Investigation that will help them use nutrition labels to determine the amount of carbohydrates, including sugar, found in foods.  As they conduct their experiment, they should think about the following questions:

• How many carbohydrates are in different foods?

• How much sugar is in different foods?

• Are carbohydrates found in all of the food groups and categories?

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Anatomy of a Triple Beam Balance. The next several slides will help students as a review for performing the mass measurements in the Lab.

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Equilibrate the Triple Beam Balance:

1. Begin by making sure that all three of the poises are set to zero. This means that they will all be to the very far left of the beams.
2. Turn the adjustment wheel under the platform until the marks line up on the balance indicator and the central graduation.
3. Once the two marks are aligned, your triple beam balance is equilibrated.

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Mass the Empty Weighing Dish:

1. Place an empty weighing dish on the balance platform.
2. Move all three of the poises as necessary to align the two marks again.
3. Once the two marks are aligned, read and record the reading from each poise.
4. This gives you the mass of the empty weighing dish.

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Mass the Sample in the Weighing Dish:

1. Place your sample in the weighing dish on the balance platform.
2. Move all three of the poises as necessary to align the two marks again.
3. Once the two marks are aligned, read and record the reading from each poise.
4. This gives you the mass of the weighing dish PLUS your sample.

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Triple Beam Balance Practice: Example Reading #1

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Triple Beam Balance Practice: Example Reading #2

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