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Transitioning Chemistry To Nutrition – The Science Behind Fats & Oils

Objectives
Students will understand the following:
That naturally occurring fats and oils are mixtures.
The relationship between carbon-carbon chemical bonds and states of matter.
The relationship between chemical bond strength, thermal oxidation, and how they relate to saturated, monounsaturated, and polyunsaturated fats.
Procedures
In discussion, assess your student’s understanding of the chemistry of naturally occurring fats and oils. Determine whether they understand that fats and oils are complex mixtures that share common chemical features, differing primarily in the occurrence of double bonds. Determine if they understand that carbon-carbon double bonds are weaker than carbon-carbon single bonds.
If students need background information on fats and oils, assign research into the chemical differences between saturated oils, monounsaturated oils, and polyunsaturated oils. Their research should give them some understanding of why an oil is classified as saturated, monounsaturated, or polyunsaturated.
Hold a post-research discussion on the student’s findings. Question students on why saturated oils are more likely to be solids at room temperature, while unsaturated oils tend to be liquids at room temperature. Encourage them to think about why saturated oils are less likely to go rancid than unsaturated oils. Why would companies prefer to use saturated oils in their products?
Conduct the following demonstration:
Weigh a 5-gram sample of each oil into separate beakers.
In a well-ventilated area (preferably a hood, or outdoors) use the butane grill lighter, ignite each oil.
Ask the students to record their observations. Specifically, what colors do they observe when each oil burns? How much smoke do they emit, and what are its characteristics?
Using their observations, can they predict how stable each oil would be when stored at room temperature? For deep frying? For baking?
Using their observations as a basis for discussion, ask students to canvas community restaurants to learn which fats and/or oils local businesses use most often. What is preferred for frying applications vs baked goods? Do businesses have a rationale for their choice? How does that compare against the health benefits of each oil?
Ask students to write a paragraph explaining how the presence, and extent of unsaturation in an oil helps determine whether it is a solid or liquid at room temperature. Based on their observations, can they predict which of the oils may be the healthiest, and why? Do their observations provide any insight into the storage stability of each oil? Students should attempt to link the observations from the demonstration with their research and class discussion. Have them share their paragraph and discuss the results.

Adaptations
Have students try comparing the influence of different cooking oils on a variety of baked goods. Assign students the task of baking a variety of items using oils rich in saturated vs. monounsaturated vs. polyunsaturated oils.

Discussion Questions
What motivated corporations to develop partially hydrogenated oils in commercial foods? Can the properties unique to partially hydrogenated oils be obtained from naturally occurring oils?
Do trans fats exist in nature? How to they appear in foods, and what makes them objectionable?
What naturally occurring oils are solids at room temperature and why? How does the number of double bonds in a given fatty acid influence its state of matter? Are the times when a chef would need to use a oil that is a solid at room temperature?
What are essential fatty acids, and which of those must humans obtain from other sources? Are they used extensively in foods? Why or why not?
Is cholesterol found in all oils? What is the plant equivalent of cholesterol, and how does that influence human health?

Evaluation
You can evaluate your students on their paragraphs using the following three-point rubric:

Three points: distinctly expresses writer’s opinion about the benefits and/or detriments of oils and fats on human health, and how chemical bonding influences those benefits; backs up opinion by clearly citing abundant information learned in research and observation; at least three sources quoted; no errors in grammar, usage, and mechanics.

Two points: adequately expresses writer’s opinion; backs up opinion by citing some information learned in research; few observations from demonstration quoted; some errors in grammar, usage, and mechanics.

One point: No clearly expressed opinion; opinion backed up by little information learned in research; no observation from demonstration quoted; many errors in grammar, usage, and mechanics.

You can ask your students to contribute to the assessment rubric by determining how much information should be considered adequate to back up an opinion, and how observations from the demonstration should influence their opinion.

Extensions
Energy Policy & Biofuels
The push for increased use of biofuels, and biodiesel in particular, has a dramatic impact on the cost and availability of oils for human consumption. Working in groups, have students make policy decisions about the use of biodiesel. Ask students to keep the following in mind when making their decisions:
What properties about an oil make it desirable for the manufacturing of biodiesel?
Chemically speaking, what is the best naturally occurring source of oil for making biodiesel, and why?
Is the best oil the most cost effective oil?
How does the use of land for making biodiesel influence human food production? What are the global effects (if any) of those choices?
What is the environmental impact of biodiesel production? In particular, consider the influence of increased fertilizer use. How does one weigh the environmental cost of fertilizer pollution against the possible environmental benefits of biodiesel use?
Why is biodiesel production so costly, when compared against traditional diesel production from an oil refinery?

When they’re done, ask groups to compare their decisions with the rest of the class. Have a discussion about the costs and benefits of biodiesel. Does pursuing widespread biodiesel production benefit mankind?

Medical Minute with Dr. Madison Mills

During the U.S.-Mexican War, more soldiers died from disease than from battle wounds. Approximately 70% of deaths were due to disease. The lesson focuses on four health threats: 1) Poor drinking water, 2) Garbage, 3) Mosquitoes, and 4) Lack of personal hygiene.

Soldiers at Fort Brown got their drinking water from the Rio Grande. However, the river was also used for bathes and as a garbage dump.

Mosquitoes were a major pest. Many army physicians suspected that mosquitoes spread diseases as well. To protect themselves, soldiers used lard, camphor oil, and cactus juice as bug spray.

Another health threat was a lack of personal hygiene. U.S. Army regulations stated that soldiers must wash their hands and face daily, their feet twice a week, and bathe at least once a week. Furthermore, soldiers were to change their underwear three times a week.
Check out the following websites for more information:
o http://www.texancultures.utsa.edu/hiddenhistory/Pages9/spurlin.htm – “Cries for Help: Medicine in the Mexican War” by Charles D. Spurlin (Institute of Texan Cultures)
o http://history.amedd.army.mil/booksdocs/civil/gillett2/amedd_1818-1865_chpt5.htm – History of the U.S. Army Medical Dept.: 1818-1865, by Mary C. Gillett (Center of Military History)

LESSON
Introduction
1. Tell students that during the U.S.-Mexican War, more soldiers died of disease than of battle wounds.
2. Tell students to stand up.
3. Use the chart on the right to divide students into two different parts of the room.
4. Tell the class that they are all soldiers who died during the U.S.-Mexican War. The bigger group died of disease and the smaller group died in combat or because of battle wounds.
Guided Lesson
1. Ask students how they can prevent disease. List responses.
2. Tell students that Dr. Mills was a surgeon during the U.S.-Mexican War. Dr. Mills gave four suggestions to prevent disease.
o Drink water upstream from where you use the bathroom
o Bury garbage
o Avoid mosquitoes
o Take bathes
3. Tell students that his advice was medical technology in 1846. Today we still do some of these things to stay healthy, but we also have modern medical technology like vaccinations.

Discovery
1. Split students into four groups.
2. Have each group create a Venn diagram comparing and contrasting the methods of medical technology during the U.S.-Mexican War with methods we have today. Help students with the first item (e.g., Take a bath is in both the 1846 and Today circles; Vaccinations is only in the Today circle.)
3. When students are finished, draw a Venn diagram on the board and complete it as a class.
4. Give each group a large piece of butcher paper with one of the following questions written on top:
o Why should soldiers drink water upstream from where they used the bathroom?
o Why should soldiers bury their garbage?
o Why should soldiers avoid mosquitoes?
o Why should soldiers take a lot of bathes?
5. Tell students to include the following on their paper:
o How their particular health practice stops disease
o Which specific diseases it prevents
o What preventative medicine or technology we use today to stop these illnesses
o Picture of the health practice the soldiers used and a picture of the health practice we use today
Wrap-up Activities
1. Have students present their findings to the rest of the class.
2. Ask students: Why is it important that soldiers stay healthy? List responses.
3. Allow students to look at the replica items.
Extensions
1. Have a class discussion on the modern health tips that the students came up with to avoid infection and disease, along with any the teacher would like to add (i.e., always wash your hands after using the restroom, keep up to date with your vaccinations, use insect repellent, etc.)
2. Ulysses S. Grant wrote he was “ten to one more afraid of [yellow fever] than the Mexicans.” Have students do computer research on Yellow Fever. How did it affect soldiers in the U.S.-Mexican War? How is Fort Brown connected to Yellow Fever? (Note that Dr. William Gorgas, who was stationed at Fort Brown in the 1880s, helped eliminate yellow fever.)
Student Evaluation/Assessment: Observe each student for class participation.

Protecting the Soldier

BACKGROUND: Information about the uniforms on the enclosed list.
For more information on U.S.-Mexican War uniforms, check out these websites:
o http://www.aztecclub.com/uniforms/uniform-a.htm
o http://www.dodgenet.com/~ghostgar/ggbook/GGbook.html
Uniforms were made out of wool because of the fabric’s properties. When soldiers sweat, wool would wick water away from the skin. If it rained, wool would absorb the water, keeping the soldier warm and dry. Wool burns very slowly. If a spark got on the soldier’s clothing, he could quickly put it out.
Wool*
o Comes from fleece of sheep, camels, llamas, goats, rabbits
o After cutting off fleece (shearing), it is sorted (graded) by the width and length of the fibers. It is then cleaned of oils, dirt, bugs, and bits of vegetation. The wool is washed and dried, untangled and combed (carded). Finally, it is twisted into yarn for weaving into fabric.
Wool Properties
o Holds a lot of water – absorbent
o Can be used to absorb blood
o Has an odor when wet
o Burns slowly, Ashes break easily
o Smells like burning hair
o Insulates in both cold and hot weather
Cotton*
o Grows from the seeds of the cotton plant as long fibers
o Removed in a cotton gin (engine). The fiber is twisted into yarn and thread. These are woven together to make the fabric.
Properties
o Holds a lot of water – 27 times its weight
o Has no odor when wet
o Burns slowly with a bright yellow frame
o Leaves puffy gray ash that breaks easily
o Smells like burning paper
*Information from AIMS Education Foundation 2001 CRAZY ABOUT COTTON
1. Ask students: What do you wear when it rains? Why do you wear those things? List responses.
2. Ask students: Do you ever wear clothes for certain groups, such as band and sports? Why do you think you wear those clothes? (Elicit: protection, allow for movement) List responses.
Discovery
1. Tell students that they will learn about the properties of wool and cotton, the fabric of the replicas.
2. Define property or have students look up the definition.
3. Ask students: What properties do fabrics have? List responses. (Elicit: absorbency, flammability)
4. Define the following or have students look up the definition.
o Wicking
o Absorbency
o Flammability
5. Tell students that they will test the wicking rate and absorbency of cotton and wool.
6. Split students into groups of four.
7. Hand out the student worksheet Material Properties.
8. Have students predict the description of each property.
9. Tell students that they will do the luster, texture, wicking, and absorbency experiments.
10. Review safety procedures.
11. See Wicking, Absorbency, and Flammability Experiments page to help students conduct the experiments.
12. When finished, have students return the materials.
13. When students are finished, conduct the flammability experiments in a safe area.
14. Have students complete their worksheets.
Wrap-up Activities
1. Tell students: During the Battle of Palo Alto, uniforms protected the soldiers.
2. Pass out the student worksheet Protecting the Soldier.
3. Ask students: Think of the following:
o Wicking Rate
o Absorbency
o Flammability

Extensions
1. Conduct further tests in the properties of wool and cotton.
2. Research how modern uniforms protect soldiers
3. Have students design their own uniform. Students must explain how the uniform offers protection.
Student Evaluation/Assessment: Observe students during the tests and for group and class participation.

Cultural Learning

1. Hand out small survey on which group they would like to look up.

2. After looking at the groups take the top three, break them into groups and have them look up stereotypes, struggles, groups or foundations that help, some team building exercises to help learn about the group.

3. Offer the mentioned websites to help the students.

4. Check on progress and offer guidence and positive reinforcement.

5. Following day, ask to give presentation of what they learned no more than 2 pages or 5 mins long.

6. Have everyone write a 2-3 page paper on what they learned about all three groups.

7. Grade papers on content.

8. Watch documentary A Class Divided to reinforce learning Diversity.

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