#2765. Artificial and Natural Chemicals

Science, level: Senior
Posted Thu Dec 12 11:54:09 PST 2002 by Simrit Burn (simrit-burn@utulsa.edu).
University of Tulsa, Tulsa, OK USA
Materials Required: varies
Activity Time: 9 weeks to 1 semester
Concepts Taught: chemistry, biology, environment, health

Essential Questions and Unit Questions

1. How do you define "chemical"?
a.Why do scientists have a system for naming chemicals?
b. What is a chemical?

2. What are differences between natural and artificial chemicals?
a. Why do we distinguish between artificial and natural chemicals?
b. How do we tell whether artificial or natural chemicals are "better"?

3. How do chemicals affect humans?
a. What are ways that "natural" chemicals affect humans?
b. What are ways that "artificial" chemicals affect humans?

4. What is food?
a. What are the effects of food processing?
b. Why is food processed?

5. How do chemicals affect the environment?
a. What are ways that "natural" chemicals affect the environment?
b. What are ways that "artificial" chemicals affect the environment?

Activities

Each activity is listed with its corresponding Essential Question (EQ) and Unit Question (UQ).

1. Formative Evaluation; Journal Entry
Students write a journal entry answering each of the five essential questions at their current level of understanding. These will be revisited and revised as we progress through the unit.

2. EQ4: What is food? UQ: Why is food processed?
"What's For Dinner?" (Project WILD) This is an introductory assignment that requires students to think about food in a way they are not used to thinking about it--in terms of the of its additives, preservatives, fertilizers, herbicides, land usage, environmental implications, etc. Most students will initially skip past the processing step by drawing a "processing factory" but providing no details. Students will begin to research why all of that unpronounceable stuff is in food. Students will pick a creative mode of presentation to present their thorough research (Power Point, poster, model, short story or poem, collage, etc.) This is where they will begin to understand the implications of the unit and the overall priorities.

3. EQ1: How do you define "chemical"? UQ: What is a chemical?
Chemical Naming Game: Should we believe the (imaginary) newspaper article, The Uninformed Oklahoman Daily, that says: "Our children are being poisoned by dangerous chemicals like METHANE CARBOXYLIC ACID [acetic acid, or vinegar when it is diluted], METHYLPROTOCATECHUIC ALDEHYDEIN [vanilla], and DEOXYRIBONUCLEIC ACID [DNA] in their school cafeteria food???" Students look at chemical names of substances they are familiar with. They play a "chemical name game" where they try to guess what something is and whether it is dangerous based on the name alone. To start, what is dihydrogen monoxide? The point of this is for the students to think about chemicals as part of every substance, not just under the sink.

4. EQ1: How do you define "chemical"? UQ: Why do scientists have a system for naming chemicals?Garden Chemicals
Students research chemicals that are commonly used in the garden using CRC handbook, Merck index, etc. They present their findings to the class. http://thechalkboard.com/Corporations/Dow/Programs/97NSTA_Lessons/Lessons/unit3.html

5. EQ1: How do you define "chemical"?UQ: What is a chemical?
Identifying Agricultural Chemicals
Students use thin layer chromatography of agricultural chemicals to solve an environmental "whodunit" problem. They will compare a sample taken from a pollution crime scene to known standards to determine which farmer is the culprit. The students develop the experiment based on their knowledge of the problem.http://thechalkboard.com/Corporations/Dow/Programs/97NSTA_Lessons/Lessons/unit3.html

6. EQ1: How do you define "chemical"?UQ: Why do scientists have a system for naming chemicals?
Overview/ Review of chemicals, their names, and how to look them up.
Class discussion about the necessity for a globally unified and standardized system of naming chemicals.

7. Formative Evaluation; Journal Entry
Students write an entry entitled: "How I Define "Chemical."

8. EQ2: What are differences between artificial and natural chemicals? UQ: Why do we distinguish between artificial and natural chemicals?
Investigating misleading food labels and advertisements.
Students find their own examples of misleading labels and ads that claim "natural" and "chemical free," or related tactics. They present them to the class with a brief write-up. Examples: (1). Supercritical carbon dioxide to decaffeinate coffee becomes "Natural Swiss Effervescence" (2). Controversial additives like MSG are labeled as monosodium glutamate, but most people do not recognize this name. (3). Warning disclaimers about saccharin and cancer risks--are they warranted? Discuss these and other examples using of chemistry and/or science knowledge.
EQ2: What are differences between artificial and natural chemicals?UQ: Why do we distinguish between artificial and natural chemicals?

9. Guest speaker in natural products chemistry. Herbal medicine and intelligent drug design: What does a medicine man have to do with X-ray crystallography? How some people have a job in science that requires them to hike, explore, and scuba dive in remote, dangerous, and even exotic locations?

10. EQ2: What are differences between artificial and natural chemicals?UQ: How do we tell whether artificial or natural chemicals are "better"?Gravimetric Analysis of Phosphorous (P2O5) in Fertilizer
Compare plant food phosphorous concentrations with fertilizer concentrations. Implications for environment: Phosphorous runoff can affect water quality by promoting weed and algae growth. Could be a debate topic later, because of restrictions on phosphorous content in fertilizers.The students develop the experiment based on their knowledge of the problem.http://chem.lapeer.org/Chem2Docs/PhosphateAnal.html

11. EQ2: What are differences between artificial and natural chemicals?UQ: How do we tell whether artificial or natural chemicals are "better"?
Compare cereals in their iron content.
Students will use a spectrophotometer to determine the amount of iron in cereals and other foods. (ChemCom)The students develop the experiment based on their knowledge of the problem.http://www.lapeer.lib.mi.us/ChemCom/Unit7/IronFoodsLab.html

12. EQ2: What are differences between artificial and natural chemicals?
Class Discussion
From these two experiments and discussion/research of other examples, students have a class discussion about artificial and natural chemicals. Students must come to the realization that "artificial" does not always mean "bad", and "natural" does not always mean "good." In reality, many other factors must be taken into consideration in order to make decisions.

13. Formative Evaluation; Journal Entry
Students write a journal entry entitled: "The differences between artificial and natural chemicals."

14. EQ3: How do chemicals affect humans? UQ: What are ways that "natural" chemicals affect humans?
Students will research historically significant topics and present their research creatively, while using science knowledge. Examples: development of penicillin, various plagues, use of manure for fertilizer and fuel, use of natural chemicals as drugs, etc. Students will present their research creatively, possibly by dressing up as a historical figure, writing a mock newspaper article, reenacting a discovery in a skit, writing a mock laboratory log of a scientist, or documenting a mock oral history of a "primitive" society.

15. EQ3: How do chemicals affect humans? UQ: What are ways that "artificial" chemicals affect humans? Students read and discuss at various news clippings and articles that discuss health-related consequences of various food additives for humans. Students begin to think about positions in support of and in opposition to relevant issues. This could lead to possible debate topics.

16. Formative Evaluation; Journal Entry
Students write a journal entry entitled: "How chemicals affect humans."

17. EQ4: What is food?UQ: Why is food processed?
Science of Dairy Products Processing: Ice Cream
Ice cream lesson with many topics: emulsifiers, freezing point depression, colligative properties, and suspension. What are the ingredients of ice cream, and why are they added? The students develop the experiment based on their knowledge of the problem. http://aged.ces.uga.edu:7201/cd2/Class%20starters,%20Mental%20Set,%20Facts,%20Figures%20&%20Ideas/The%20Science%20of%20Ice%20Cream.doc
Expansion: Where/when was ice cream invented, and how did they keep it cold?

18. Formative Evaluation; Journal Entry Students write a journal entry entitled: What is food?

19. EQ5: How do chemicals affect the environment? UQ: What are ways that "natural" chemicals affect the environment?
Can you ever have too much of a good thing, like chicken manure? Students study water quality issues in their area. For instance, there is controversy in Oklahoma about chicken farm waste polluting rivers. http://www.tulsawater.com/watreduc.html

20. EQ5: How do chemicals affect the environment?UQ: What are ways that "natural" chemicals affect the environment?
Compost
Students make their own compost. Working in small groups, they decide what quantifiable things they want to learn about compost and how they want to learn it. For instance, pH, solubility, rates of decomposition, exposure to light/air, etc. How do these factors affect the functions of compost? They write a "grant proposal" to be submitted to a funding panel (me), and then they execute the experiment. Students present their research to the class. The students develop the experiment based on their knowledge of the problem.http://www.yale.edu/ynhti/curriculum/units/1997/7/97.07.06.x.html#j

21. EQ5: How do chemicals affect the environment? UQ: What are ways that "artificial" chemicals affect the environment?
Students research the various types of pesticides, and "non-chemical alternatives to traditional pesticide strategies.http://www.gatewest.net/~green/from/l3.html#goalsl3

22. EQ5: How do chemicals affect the environment? UQ: What are ways that "artificial" chemicals affect the environment?
DDT simulation and Excel exercise
What is the bioaccumulation affect? Students play a game that simulates the bioaccumulation affect of DDT. They use Excel spreadsheets to find out how DDT exposure increases for organisms at the top of the food chain.

23. Formative Evaluation; Journal Entry
Students write a journal entry entitled: "How chemicals affect the environment."

24. Formative Evaluation;l Journal Entry
Students write a journal entry answering each of the five essential questions at their current level of understanding. They also reread their previous journal entry, and write about how their views have since changed. In the entries, they address the "What's for Dinner?" activity.

25. Core Performance Task: Debate
The core performance task at the end of the unit will be a series of small group debates or mock-trials about chemical issues that have physiological and/or environmental significance. The students will research their points of view in terms of science, politics, economics, etc. The students will use what they learned in the unit and their chemistry knowledge to support their arguments, refute others' arguments, and to comment on the outcome of peer debates. Students will self-assess after the debate by composing reflections on their arguments, their opponents' arguments, and the final judgment for each debate. Students could possibly choose debate topics throughout the unit as they learn.

Rubric for Debate

A. Explanation of Research
4-You will present a sophisticated, in-depth, explanation of thorough background research.
3-Developed explanation of adequate background research.
2-Intuitive explanation of incomplete background research.
1-Naïve explanation of incomplete and/or inappropriate background research.

B. Application of Scientific Knowledge and Principles
4-You will demonstrate masterful, skilled application of science.
3-Able application of science.
2-Apprentice or inadequate application of science.
1-Novice or incorrect application of science.

C. Perspective Regarding Relevant Societal Factors (e.g. Political, Social, Economic, etc.)
4-You will demonstrate an insightful, thorough, well-developed, and well-supported perspective regarding the broader implications surrounding the issues.
3-Perspective is considered, but sometimes lacks thorough development and/or evidence.
2-Perspective is aware, but completely lacks development and/or evidenced.
1-Perspective is uncritical, undeveloped, or has major oversights of pertinent issues.