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6-8 > Human Body
Grade level: 6-8 Subject: Human Body Duration: One class period
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Objectives | Materials | Procedures | Adaptations | Discussion Questions | Evaluation | Extensions | Suggested Readings | Links | Vocabulary | Academic Standards | Credit
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Objectives
 



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Students will understand the following:
1. Identical twins are genetically identical.
2. For this reason, twins separated at birth and later reunited have been subjects for scientific researchers investigating the influence of heredity and environment on human personality.
Materials

For this lesson, you will need:
Research materials on genetics, particularly on twins
Computer with Internet access
Procedures

1. Initiate a class discussion about the heredity-versus-environment issue. Do your students think that heredity is the primary influence over human personality development, or do they think that a child’s experiences and associations are more influential?
2. Continue the discussion by asking students to come up with ways the question could be scientifically investigated.
3. If your students have not brought up twin studies, ask them why a pair of identical twins who had been separated at birth, raised in different environments, and reunited as adults could be excellent subjects for a study of the effects of heredity versus environment on personality development. (Make sure students understand that identical twins are genetically identical.)
4. Ask the class how they would interpret the following sets of data: (a) each identical twin in the pair has a very different personality and lifestyle; (b) the twins are unbelievably similar, not only in physical appearance but also in personality and lifestyle.
5. Divide your class into groups, and challenge each group to devise a questionnaire with at least 10 questions they would ask each of the twins in a study designed to weigh the effects of heredity and those of environment on personality development.
6. Have students do research on the Internet to find the results of actual studies that have been done using separated identical twins as subjects.
7. Have students play the roles of the separated identical twins and fill in their own questionnaires based on findings from their research.
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Adaptations

Adaptations for Older Students:
Have students contact a twin registry such as the Gregor Mendel Institute of Medical Genetics and Twin Studies (located in Rome) or the Minnesota Center for Twin and Adoption Research to find out about actual research being conducted. What methods are being employed to collect data? How is this research being used to benefit society?
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Discussion Questions

1. Explain what steps should be taken by scientists studying twins to avoid possible invasion of privacy.
2. What might explain the extraordinary similarities between identical twins separated soon after birth, reared in different environments, and reunited for the first time as adults?
3. What do twin studies indicate about the influence of the environment and the complex interaction of genes on our personality, intellectual ability and emotions such as happiness?
4. Although telepathic communication has not been proven to exist among twins, describe what consequences might arise if such communication were possible. Could telepathy be used responsibly? What are the ethical considerations associated with telepathic communication?
5. The environment before birth is critical to the development of the unborn child. Prenatal influences may lead to differences in size, appearance and psychological development. Describe the function of the following structures: chorion, amniotic sac, placenta and umbilical cord. How might the functioning of these structures be compromised if there is more than one embryo developing?
6. Describe the four possible mechanisms in which identical twins could form. Why is there a point during pregnancy after which the developing twins' health may be in jeopardy?
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Evaluation

You can evaluate your students on their questionnaires using the following three-point rubric:
Three points:all questions thoughtfully designed; questions well phrased and unambiguous; at least 10 questions
 
Two points:most questions thoughtfully designed; phrasing of some questions awkward or unclear; at least 10 questions
 
One point:questions reflect little thought; phrasing of many questions awkward or unclear; fewer than 10 questions
 
You can ask your students to contribute to the assessment rubric by determining what kinds of questions would advance the study.
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Extensions

Imagine Your Twin
Suggest the following scenario to your students: “You have just learned that you have an identical twin you have never met. You are about to meet for the first time, and you have so many questions. Will my twin be like me or different? Will we get along?
Will we like each other?” Have students, keeping this scenario in mind, make a list of physical traits they think they and their twins might have in common. Next, have them compile a list of behavioral traits they think they would share with their twins. The list should include habits, mannerisms, ways of expressing emotions, likes, dislikes, and so on. Finally, students could write short stories about their meetings with their long-lost twins.

Twin Folklore
Writers and anthropologists have noted the religious beliefs, rituals, myths, and legends that have revolved around twins throughout time. Art, statuary, literature, and temples have been inspired by twins. With your class, delve into the world of twin folklore, and have groups of students prepare presentations for the class on particular legends about twins.

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Suggested Readings

"Annual Twins Day Festival More Than Just Fun and Games"
National Public Radio, weekend edition, Aug 6, 1995; program number 1135
The transcript of this radio program discusses the "Twins Day Festival" in Twinsburg, Ohio, which annually attracts 3,000 sets of twins and the researchers who wish to study them.

"Worldwide: U.S. Twin Births Rose 42%"
Wall Street Journal, February 14, 1997
How might society be different if there were as many twins as everyone else? That may soon be a reality, given the trend of increasing twin births. This article tells why that trend is occurring.

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Links

Welcome to the TWINSource homepage
Dedicated to the topic of identical twins, created by an identical twin.

Monoamniotic.org
This site includes discussions and numerous links to support and inform parents of monoamniotic twins.

Jimtwins.html


Twins Days


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Vocabulary

Click on any of the vocabulary words below to hear them pronounced and used in a sentence.

speaker    ultrasound
Definition:A technique involving the formation of a two-dimensional image used for the examination and measurement of internal body structures and the detection of bodily abnormalities--also known as sonography.
Context:These pictures are captured with ultrasound.

speaker    genes
Definition:A specific sequence of nucleotides in DNA or RNA that is the functional unit of inheritance controlling the transmission and expression of one or more traits.
Context:Identical twins are a miracle of nature: two people with the same set of genes.

speaker    identical twins
Definition:Two persons closely resembling each other who share the same set of genes.
Context:Most identical twins have identical backgrounds.

speaker    telepathically
Definition:Communication from one mind to another by extrasensory means.
Context:It has been suggested that twins have the ability to communicate telepathically.

speaker    behaviorism
Definition:A school of psychology that takes the objective evidence of behavior (as measured responses to stimuli) as the only concern of its research and the only basis of its theory, without reference to conscious experience.
Context:American psychology went through a reign of behaviorism.

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Standards

This lesson plan may be used to address the academic standards listed below. These standards are drawn from Content Knowledge: A Compendium of Standards and Benchmarks for K-12 Education: 2nd Edition and have been provided courtesy of theMid-continent Research for Education and Learningin Aurora, Colorado.
 
Grade level:6-8
Subject area:life science
Standard:
Understands the genetic basis for the transfer of biological characteristics from one generation to the next.
Benchmarks:
Knows that in sexual reproduction, an egg from a female unites with a sperm from a male to begin the development of a new individual that has an equal contribution of information from its mother and its father; sexually produced offspring are never identical to either of their parents.

Grade level:6-8
Subject area:life science
Standard:
Understands the genetic basis for the transfer of biological characteristics from one generation to the next.
Benchmarks:
Knows that the characteristics of an organism can be described in terms of a combination of traits; some traits are inherited and others result from interactions with the environment.

Grade level:6-8
Subject area:life science
Standard:
Understands the genetic basis for the transfer of biological characteristics from one generation to the next.
Benchmarks:
Knows that hereditary information is contained in genes, which are located in the chromosomes of each cell; each gene carries a single unit of information, and an inherited trait of an individual can be determined by either one or many genes.

Grade level:9-12
Subject area:life science
Standard:
Understands the genetic basis for the transfer of biological characteristics from one generation to the next.
Benchmarks:
Knows that in all organisms, the instructions for specifying the characteristics of the organism are carried in DNA; the chemical and structural properties of DNA explain how the genetic information that underlies heredity is both encoded in genes (as a string of molecular "letters") and replicated (by a templating mechanism).

Grade level:9-12
Subject area:life science
Standard:
Understands the basic concept of evolution of a species.
Benchmarks:
Knows that heritable characteristics, which can be biochemical and anatomical, largely determine what capabilities an organism will have, how it will behave and, hence, how likely it is to survive and reproduce.

Grade level:9-12
Subject area:technology
Standard:
Understands the nature of scientific knowledge.
Benchmarks:
Knows that from time to time, major shifts occur in the scientific view of how the world works, but usually the changes that take place in the body of scientific knowledge are small modifications of prior knowledge; change and continuity are persistent features of science.

Grade level:9-12
Subject area:technology
Standard:
Understands the nature of scientific inquiry.
Benchmarks:
Knows that there is no fixed procedure called "the scientific method," but that investigations involve carefully collected, relevant evidence, logical reasoning and some imagination in developing hypotheses and explanations.

Grade level:6-8
Subject area:technology
Standard:
Understands the nature of scientific inquiry.
Benchmarks:
Knows that scientific investigations sometimes result in new ideas, objects and phenomena for study, new methods or procedures for an investigation, or new technologies to improve the collection of data; all of these results lead to new investigations.

Grade level:9-12
Subject area:technology
Standard:
Understands the nature of scientific inquiry.
Benchmarks:
Knows that hypotheses are widely used in science for choosing what data to pay attention to and what additional data to seek, and for guiding the interpretation of the data (both new and previously available).

Grade level:9-12
Subject area:technology
Standard:
Understands the scientific enterprise.
Benchmarks:
Knows that individuals and teams have contributed and will continue to contribute to the scientific enterprise; doing science or engineering can be as simple as an individual conducting field studies or as complex as hundreds of people working on a major scientific question or technological problem.

Grade level:6-8
Subject area:technology
Standard:
Understands the interactions of science, technology and society.
Benchmarks:
Knows that scientific knowledge and the procedures used by scientists influence the way many individuals in society think about themselves, others and the natural environment; societal challenges often inspire questions for scientific research and social priorities often influence research priorities through funding.

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Credit

Lisa Lyle Wu, science teacher, Thomas Jefferson High School for Science and Technology, Alexandria, Virginia.
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