Lab 1: Sweet Saccharide

Teacher Preparation:

1. Review information found in the Background Agricultural Connections section of the lesson, lesson Procedures, and the attached Essential Files.
2. Prepare lab materials for each group. Each group will need three unknown samples and a control. Label each cup as “Sample A”, “Sample B”, “Sample C”, or “Control”.
3. For each sample, pour ¼ cup of liquid (juice or water) into a clear, plastic cup.
   • Water = Control
   • Unknown Sample A = Apple (100%) Juice
   • Unknown Sample B = White Grape (100%) Juice
   • Unknown Sample C = Water mixed with 1/2 Tbsp. sugar. Color the sugar water yellow using food coloring. The color should be similar to the apple juice.
     • To ensure glucose concentrations can be properly measured during the lab, do not purchase diet or sugar free juices.
     • Timesaver: Prepared samples may be reused for other classes.

Procedures:

1. Distribute lab materials. It is recommended that materials are organized into stations for easier distribution. Students should be arranged in small groups of 4-5. Each group should receive the lab supplies outlined in the Materials section as well as 1 copy of the Sweet Saccharide lab sheet and one copy of the Sugar Solutions student handout.
2. Ask students to read Sugar Solutions and complete the "Think About It" questions for this lab investigation.
3. Before beginning the lab investigation:
   1. Require students to wash their hands.
   2. Emphasize the importance of practicing good food safety behaviors by not consuming substances used as part of the lab investigation.
4. Launch the lab by showing students the Sweet Saccharide video lab demonstration. The video will demonstrate procedures students will follow during the lab, including directions on how to accurately read the glucose strips. The glucose strips must be read at exactly 30 seconds.
5. Instruct students to observe and make a prediction about their unknown substances. Before testing unknown samples, students should practice obtaining consistent results using the control (water) sample. Students should find the following results:
   • Control Sample (Water): The water sample will produce a negative test for glucose.
   • Unknown Sample A (Apple Juice): Apple juice will be positive for glucose. The apple juice will produce a color that is slightly less brown than grape, however both will produce a positive test for glucose (dark brown color on strip). When identifying samples, students should conclude Sample A is apple juice because the strips detected a glucose level smaller than sample B. The data in Table C indicates the % of glucose in Apple Juice is between samples B and C.
   • Unknown Sample B (Grape Juice): Grape juice will be positive for glucose. The concentration of glucose will prove to be higher compared to the other samples. When identifying samples, students should conclude Sample B is grape juice because the strips detected the largest glucose concentration. Looking at the data in Table C, Grape Juice has the largest % glucose.
   • Unknown Sample C (Sugar Water): The sugar water should produce a negative test for glucose because it consists primarily of sucrose. The amount of glucose present is too small to be detected by the testing strip. An enzyme (sucrase) would have to be introduced in order to break sucrose down into its components (glucose and fructose). It is important to note that the test results will be identical to the control. This should indicate to students that the sample contains little to no glucose. When identifying samples, students should conclude Sample C is sugar water because the strips did not detect glucose and the data in Table C indicates the sample has the smallest % glucose.
6. Allow students to work in small groups to finish the Sweet Saccharide lab sheet to further explore the topic and respond to lab questions.
7. Follow-up with a class discussion about dietary carbohydrates, the role they play in providing energy to the body, and the consequences of consuming too many “empty calories.” See Enriching Activities for ideas on how to further extend this lab.

Lab 2: Super Solutions

Teacher Preparation:

1. Review information found in the Background Agricultural Connections section of the lesson, lesson Procedures, and the attached Essential Files.
2. Prepare materials for the teacher demonstration and for each group.
3. The teacher demonstration will show students a heated (supersaturated) solution. After saturating the solution, you will divide the liquid among 6 (1 per group) Styrofoam cups. The solution will be very hot. It is important to allow cooling time before students observe the solution. Students will need to observe the solution starting with conclusion question #2.
4. Each group will need 100mL water in a graduated cylinder or other container, and 1 bag containing 25g of white sugar. Keep extra sugar on hand during the lab investigation. Some groups may need additional sugar when creating their saturated solutions.
5. If needed, identify 2-3 students to help with the teacher demonstration (e.g. measuring, recording data on board).
6. Students may need to be taught or reminded how to use a triple beam balance, including how to mass granular solids. General directions are provided for students in their procedure.
   • Timesavers: To save time pre-measure the 500g of sugar needed in the demonstration. Separate the sugar into two plastic bags containing 250g each. If time is a limitation, use the demonstration video in place of the in-class teacher-led demonstration. Provide students with the data below after your class has viewed the video.
     

Procedures:

1. Consider having your students research common solutions in everyday living (particularly those we consume) prior to beginning the lab investigation.
2. Distribute lab materials. It is recommended that materials are organized into stations for easier distribution. Students should be arranged in small groups of 4-5. Each group should receive the lab supplies outlined in the Materials section as well as 1 copy of the Super Solutions lab sheet.
3. If students did not complete Lab 1, ask students to read the Sugar Solutions student handout and complete the focus questions.
4. Before beginning the lab investigation:
   1. Require students to wash their hands.
   2. Emphasize the importance of practicing good food safety behaviors by not consuming substances used as part of the lab investigation.
   3. In this investigation, students should be allowed to taste their final product as part of the lab investigation.
5. Begin the student lab investigation by asking students to make a prediction about which solution will contain the greatest concentration of sugar.
6. Launch the teacher demonstration. The demonstration will show students how to create a heated (super-saturated) solution. Write data (grams of sugar needed to saturate the solution) on the board for students to record. Follow instructions below for teacher demonstration:
   1. On high heat, quickly heat 100mL of water.
   2. While the water heats, measure out 250 grams of sugar.
   3. Once the water is hot (simmering, but not boiling), begin adding sugar 50-100 grams at a time. Allow the sugar to dissolve before adding more sugar.
   4. Continue heating the solution and adding sugar, until additional sugar will not dissolve. If you have to add additional sugar beyond the initial 250 grams, measure and add sugar in 50-gram increments.
   5. Record the specific amounts of water (mL) and sugar (grams) needed to create the super-saturated solution. Students should record the amount of carbohydrate (sugar) needed to create a super-saturated heated solution in Table A.
   6. Divide the hot solution into separate Styrofoam cups (1 per group of students) and set aside, allowing each to cool for later observation.
7. Launch the student portion of the lab investigation. Start by showing the Super Solutions Lab 2 demonstration video. Students should find that the heated sugar solution (super-saturated) had the greatest amount of sugar in it, followed by the cold solution (saturated), and regular solution (fresh orange juice).
   • Solution: At the end of the lab, students will make freshly squeezed orange juice. The natural sugar in the orange juice is a solution. Solutions consist of two or more substances. The orange juice is not fully saturated with sugar particles. They are different from colloids and emulsions. Colloids are solutions with particles dispersed throughout. Emulsions are a suspension of two substances that do not mix together.
   • Saturated Solution: The cold solution represents a saturated solution. A saturated solution is created when a maximum amount of solute (sugar in this case) is dissolved into another substance (solvent). Environmental conditions (e.g. temperature) can result in changes to solubility.
   • Super-saturated Solution: The heated solution represents a super-saturated solution. Generally, the higher the temperature, the greater the solubility of a solid in a liquid (e.g. sugar in water). Super-saturated solutions have been forced to dissolve a greater amount of solute than it is normally capable of holding. This type of solution is unstable. Agitation (e.g. insertion of a wooden skewer) will cause the formation of crystals.
8. Allow students to work in small groups on the Super Solutions lab sheet to further explore the topic and respond to lab questions.
9. Follow-up with a class discussion about solutions commonly found in real life (e.g. soft drinks, sweet tea, simple syrup), and the relevance to overall health and energy balance. See Enriching Activities for ideas on how to further extend this lesson.

Concept Elaboration and Evaluation

After conducting these activities, review and summarize the following key concepts

• Sugar (sucrose) is extracted from the sugarcane and the sugar beet plants.
• Many common drinks such as soda pop and juice contain high levels of sugar.
• Some food products are naturally sweetened, meaning they contain sucrose, fructose, or glucose. Other foods have added sugar.
• The solubility of a substance is the amount of solute that will dissolve in a solvent.