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• explore what causes rare diseases and
Steps 1 and 2
• assume the roles of medical officers in charge of the health of
soldiers at an army post.
Arrange the class into pairs. Explain that they will look at a list of
Page 56
infirmary visits for the previous week and look for patterns that suggest Step 3
a health concern.
Give each pair a copy of Masters 2.1 and 2.2, and ask students to read Page 57
over the reasons for the visits.
Step 4-p
Ask, “What are two general reasons why soldiers reported to the
Page 57
infirmary?”
Step 5-p
Remind students about the three general causes of disease:
Page 58
• infectious agents,
Step 6
• heredity (genetics), and
• environmental toxins.
Ask, “Which of these three causes is most likely to be responsible for a health problem that can spread throughout the post?”
Display Master 2.1.
Page 58
• Ask a volunteer to summarize the reasons that soldiers came to
Steps 7
the infirmary.
and 8
• Record and display these reasons.
• Ask, “Do any patterns or cases worry you?”
Mention that one or more types of infectious disease may be present
Page 58
on the post. Ask, “How can we tell whether or not a soldier has a
Step 9
bacterial infection?”
Explain that people can order tests for bacterial infections.
Page 59
• Test 1 looks for infections by bacterial species associated with
Step 10
pinkeye, sore throats, and infected cuts and abrasions.
• Test 2 looks for infections associated with skin rashes caused by
Rocky Mountain spotted fever or Lyme disease bacteria and for
exposure to poison ivy.
Instruct pairs to decide and then record on Master 2.1 which lab tests Page 60
(if any) to order for which soldiers and why.
Step 11-p
Give each pair a copy of Master 2.3. Ask students to summarize in Page 61
their notebooks the cases that could spread throughout the post and
Steps 12-p
to describe how they were treated.
and 13-p
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Rare Diseases and Scientific Inquiry
Activity 2: Is a Rare Disease Present?
Estimated time: 40 minutes
Page and Step
Explain that one week has gone by, and you are ready to discuss
Page 62
patient outcomes from Week 1 and to present a list of new infirmary
Steps 1-p
visits. Give each student pair a copy of Master 2.4, and ask students to and 2-p 1
look it over.
Ask, “Did you learn anything that causes you to be concerned?”
Page 63
Step 3-p
Give each pair a copy of Master 2.5, and ask students to look it over.
Page 63
Instruct pairs to summarize in their notebooks the reasons soldiers
Step 4-p
came to the infirmary.
Ask volunteers to report what they wrote in their notebooks, display
Page 63
their responses, and discuss.
Step 5
Ask, “Is there any evidence of a bacterial infection spreading
Page 63
2
throughout the post?”
Step 6
Explain that you are concerned about the serious foot infection.
Page 64
• Observe that bacterial species A seems to cause both sore throats
Step 7
and the foot infection.
• Ask, “Can the same bacterial species be responsible for causing
two different diseases?”
Explain that the foot infection could be caused by flesh-eating disease.
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Instruct students to look up the disease in the Medical Reference
Step 8
Manual.
3
Give each pairs a copy of Masters 2.6 and 2.7 . Instruct students to use Page 64
Master 2.6 to answer the questions on Master 2.7.
Step 9-p
Ask volunteers to report their answers to the questions on
Page 65
Master 2.7.
Step 10
4
5
Lesson 2
73
Activity 3: How Rare Is Rare?
Estimated time: 30 minutes
Page and Step
Observe that bacterial species A is common and causes strep throat. It
Page 66
can also cause the rare flesh-eating disease. Explain that the odds of
Step 1
getting flesh-eating disease are 1 in 100,000.
Arrange the class in groups of four. Give each group
Page 66
• 1 small container with 9 baby lima beans and 1 baby lima bean
Step 2
colored red and
• 1 large container with 99 baby lima beans and 1 baby lima bean
colored red.
Display this statement: “The odds of coming down with flesh-eating
Page 66
disease this year are 1 in 100,000.”
Step 3
Explain that the red bean represents a person who may come down Page 66
with flesh-eating disease.
Step 4
• Have one student from each group pick a bean from the small
container without looking.
• Ask, “Did anyone get a red bean?”
Display this: “1/10.” Explain that the odds of picking a red bean were 1
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in 10.
Step 5
Have another student from each group pick a bean from the large
Page 66
container. Ask, “Did anyone get a red bean?”
Step 6
Display this next to 1/10: “× 1 /100.” Explain that the odds of picking a Page 66
red bean were 1 in 100.
Step 7
Tell students to place the selected beans back into the large container Page 67
and mix. Have another student once again pick a bean from the large
Steps 8 and 9
container. Ask, “Did anyone get a red bean?”
Display next to 1 /100, “× 1 /100.” Explain that, as before, the odds of Page 67
picking a red bean were 1 in 100.
Step 10
Explain that this activity modeled the 1 in 100,000 probability of
Page 67
coming down with flesh-eating disease.
Steps 11 and 12
• Display the answer to the probability calculation:
“1/10 × 1/100 × 1/100 = 1/100,000.”
• Explain that to get flesh-eating disease, a group would have had
to pick the red bean from the small container and pick it again
both times from the large container.
Conclude the lesson by asking,
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• “What are two reasons why flesh-eating disease is so rare?”
Step 13
• “Which two general causes of disease interacted to allow flesh-
eating disease to develop?”
= Involves copying a master.
= Involves making a transparency.
74
Rare Diseases and Scientific Inquiry
Lesson 3
The Difficulty of Diagnosis
1
2
Explain
At a Glance
Overview
3
Some people who have a rare disease struggle to obtain a proper diagnosis.
In Lesson 3, students become involved with a case study of a boy with the rare genetic disease Marfan syndrome. Because Marfan syndrome shares
symptoms with other, more-common diseases, it can take a long time for
patients to receive the correct diagnosis. Students observe how problems with a single gene can affect many different body systems. The lesson
concludes with students considering comments made by young people
with Marfan syndrome.
Major Concepts
• Because some rare diseases have symptoms similar to more-common
4
diseases, obtaining a correct diagnosis can be difficult.
• A rare disease may have a genetic cause.
• A rare disease, like some common diseases, may affect many different
body systems at the same time.
• People with rare diseases may sometimes be viewed as being “different”
by their peers and other members of society.
Objectives
After completing this lesson, students will have
• observed how problems in a single gene can affect many different body systems,
5
75
• encountered the difficulty often associated with diagnosing a rare
disease, and
• recognized that people affected by Marfan syndrome face challenges in their lives, and despite these challenges, they have the same hopes and dreams as others and perhaps a unique view about the value of health.
Teacher Background
Consult the following sections in Information about Rare Diseases and
Scientific Inquiry:
2.0 The Impact of Genomics on Rare Diseases (pages 24–26)
5.2 Marfan Syndrome (pages 29–31)
In Advance
Web-Based Activities
Activity
Web Component?
1
Yes
2
No
3
Yes
Photocopies, Transparencies, Equipment, and Materials
Photocopies and Transparencies
Activity 1: A Parent’s Dilemma
For Classes Using the Web-Based Version:
1 transparency of Master 3.1
1 copy of Master 3.2 for each student
For Classes Using the Print-Based Version:
1 transparency of Master 3.1
1 copy of Master 3.2 for each student
1 copy of Masters 3.3, 3.4, 3.5, and 3.6 for each group of 4 students (each group member gets a different master)
Activity 2: Connective Tissue
1 transparency of Master 3.7
Activity 3: A Common Thread
For Classes Using the Web-Based Version:
1 copy of Master 3.8 for each pair of students
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Rare Diseases and Scientific Inquiry
For Classes Using the Print-Based Version:
1 copy of Masters 3.8, 3.9, and 3.10 for each pair of students
1 transparency of Master 3.11
Equipment and Materials
For Activities 1 and 3, the Web-based versions, you’ll need computers 1
with Internet access.
For Activity 2, you’ll need, per student pair:
• 1 new (never-before-stretched) rubber band from a dish labeled “A”
• 1 previously stretched rubber band from a dish labeled “B”
• 1 paper clip
• 1 soda can containing about 2 ounces of water*
• 1 meter stick
*Any weight of 2–3 ounces (55–85 grams) that can be easily attached to
the paper clip will work.
2
Preparation
Activity 1
For classes using the Web version, verify that the computer
lab is reserved for your class or that classroom computers
are set up for the activities. Refer to Using the Web Site for
details about hardware and software requirements for the
Web site. Check that the Internet connection is working properly.
Log on to the Web Portion of Student Activities section of the Web site: 3
http://science.education.nih.gov/supplements/rarediseases/student
Select “Lesson 3: The Difficulty of Diagnosis.”
Activity 2
Each pair of students will need a meter stick, a rubber band that has been repeatedly stretched (about 25 times), and a rubber band that hasn’t been stretched. Use the same color rubber band for both stretched and nonstretched 4
rubber bands so they look identical. Place the nonstretched rubber bands into a dish labeled “A” and the stretched rubber bands into a dish labeled “B.”
Activity 3
For classes using the Web version, verify that the computer
lab is reserved for your class or that classroom computers
are set up for the activities. Set the computers to the
opening screen for Activity 3, as you did for Activity 1.
5
Lesson 3
77
Procedure
Note: This is an Explain lesson. It is designed to build on students’
common experience learning about the causes of rare diseases. Students
assume the roles of staff working for a medical geneticist. The scenario gives students a chance to apply their understandings about disease and scientific inquiry to explain the underlying cause of diverse symptoms
displayed by a patient. In this lesson, students will use what they learned in the first two lessons about diagnosing disease. At this point, students should be able to construct more strongly supported explanations. They
should focus on scientific principles as opposed to simply expressing their ideas and offering preliminary explanations.
We chose Marfan syndrome for this lesson because it is a rare disease
caused by mutations in a single gene. It affects different body systems and can be difficult to diagnose. Patrick, the fictional patient, is a teenager who wants to play sports but has medical problems that cause his parents to worry about his participation. This realistic scenario is designed to be engaging to middle school students.
The mutations associated Marfan syndrome affect connective tissue.
Realizing that students have little knowledge about connective tissue and its functions, we designed Activity 2 to give students a simple model that illustrates how the connective tissue of people with Marfan syndrome
differs from that of healthy people.
Activity 1: A Parent’s Dilemma
Estimated time: 25 minutes
1.
Begin the lesson by explaining that you will investigate a case
study of a child who has a rare disease. In addition to the
difficulty of obtaining a correct diagnosis, students will see how
patients and their families cope with this particular rare
disease.
2.
Display Master 3.1, To Play or Not to Play? Ask for different volunteers to read each paragraph aloud to the class.
3.
Ask students to place themselves in the position of Patrick’s
parents and then ask, “Would you allow Patrick to try out for
the basketball team?”
Students’ responses will vary. Many students will conclude that
Patrick should be allowed to play basketball since none of the
doctors said that he shouldn’t play. Some students may know of a
friend or family member with one of the conditions described and
base their opinion on that example. At this time, don’t express an
78
Rare Diseases and Scientific Inquiry
opinion yourself about whether Patrick should be allowed to play
basketball.
Tip from the field test: Consider taking a poll of the
students in the class. Ask how many would allow
Patrick to play basketball. Later, at the end of the
lesson, poll students again and discuss why their
1
opinions have changed or stayed the same.
4.
Comment that this discussion about playing basketball and
health prompted Patrick’s parents to look into the family’s
medical history. Especially on his father’s side of the family,
some relatives have had medical problems similar to Patrick’s.
Several have had serious heart problems. The parents are
worried that an inherited disease might run in the
family.
2
If necessary for your students, relate the idea of inherited disease to genes and mutations. You may need to explain that some diseases
that run in families are caused by mutations to a single gene
and that by looking at a family tree, doctors can sometimes see
evidence for a genetic cause for the disease. This connection will be
important later in the lesson.
5.
Explain that Patrick and his parents next visited a medical
geneticist, a doctor who specializes in diagnosing people with
genetic diseases. A medical geneticist works with other doctors
3
when it appears that a patient’s disease may have a genetic
cause.
Content Standard C:
Every organism
Again, if necessary, you may want to explain that many (though not
all) genetic diseases are rare. This means that a family doctor may
requires a set of
never have seen a patient with the rare disease and not think of it
instructions for
when making a diagnosis.
specifying its traits.
Heredity is the
6.
Explain that for the rest of Activity 1, students will work in
passage of these
groups of four. They will assume the roles of medical specialists
instructions from one
assisting the medical geneticist in diagnosing Patrick. Because
4
generation to another.
Patrick has medical problems that affect different body systems,
each member of the group will be responsible for a different
body system. The four specialties (and their body systems)
are
• orthopedist (skeletal system),
• ophthalmologist (visual system),
• cardiologist (heart and circulation system), and
• pulmonologist (respiratory system).
5
Lesson 3
79
Note: During Lesson 5, students will create an informational poster about either Marfan syndrome or childhood leukemia. With this in
mind, you might want to stress the need to take good notes during
Lessons 3 and 4.
Content Standard C:
The human organism
has systems for
(For print version, skip to Step 7-p on page 81.)
digestion, respiration,
In classrooms using the Web version of the activity:
reproduction,
circulation, excretion,
7-w. Give each student one copy of Master 3.2, Medical Specialty
movement, control,
Report Form. Direct students to their computer stations.
and coordination,
and for protection
Web browsers should be at
from disease. These
http://science.education.nih.gov/supplements/rarediseases/student
systems interact with
each other.
This is a menu page that contains a link for this activity.
8-w. Instruct students to click on “Lesson 3: The Difficulty of
Diagnosis,” and then “Activity 1: A Parent’s Dilemma.” Then they
should click on one of the medical specialties (“Activity 1:
Orthopedist,” “Activity 1: Ophthalmologist,” “Activity 1:
Cardiologist,” or “Activity 1: Pulmonologist”).
Each group member must obtain information about Patrick that
corresponds to the medical specialty the group is assigned. Each
medical specialty contains a report from Patrick’s doctor. To help
them make sense of this report, each medical specialty includes a
link to a Medical Reference Manual: Disorders of Connective Tissue,
which provides helpful background information. If you have enough
computers for each student, then the process will move quickly.
9-w. Explain that information about Patrick’s medical history and
physical exam is provided for each medical specialty. Instruct
students to
• review their assigned medical specialty;
• record on Master 3.2 what they learn about Patrick’s
medical history;
• record on Master 3.2 what they learn from Patrick’s physical
exam; and
• use the Medical Reference Manual to learn about possible
causes of Patrick’s medical problem, and then record them
on Master 3.2.
Continue with Step 10 on page 81.
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Rare Diseases and Scientific Inquiry