Master 3.2, Comparison Guide
1 copy per student
For Web version
and 1 transparency
2
Master 3.1, Survey
1 transparency
For print version Master 3.3, Add Health Study
1 copy per student
Data
team and 1
transparency
Master 3.4, Class and Add
1 copy per student
Health Study Comparison
and 1 transparency
3
Master 3.5, Analysis Guide
1 copy per student
For Web version
and 1 transparency
3
Master 3.5, Analysis Guide
1 copy per student
For print version
and 1 transparency
Master 3.6, Influences on
1 copy per student
Physical Activity Behaviors
team and 1
transparency
Materials
Activity
Materials
1
None
2
Colored pencils
Calculators
3
Colored pencils
Calculators
58
Preparation
Activity 1
If your school district requires parental consent for students to fill
out surveys, please distribute and then collect signed copies of the
Permission Letter master at the end of the supplement, after Master 5.2.
Otherwise, no preparation is necessary.
Activity 2
If you are using the Web version of this activity, you must establish a unique class code for each class that will enter data into the Web
database. To do this, go to the URL http://science.education.nih.gov/
supplements/healthy/student. This is a menu page from which you
can access the Teacher Administration page by clicking on “Lesson
3—Database Administration.” The Database Administration page is
for teachers only and allows you to register your classes and create
a unique identifier for each class data set. Enter the user name
healthyadmin and the password admin, and then click “Sign In” to
enter this site and register your classes. Write down the class code(s)
that appear on screen. The class code(s) will also be sent to you by
e-mail. Verify that the computer lab is reserved for your classes for
Activities 2 and 3 or that classroom computers are ready to use.
If you are using the print version of this activity, no other preparation is needed.
Activity 3
Same as for Activity 2.
Activity 1: Physical Activity Survey
Procedure
(Or, What Do You Do?)
For classes using the Web or print versions of this activity: 1. Ask students to raise their hands if they have ever taken a
survey. Then ask them to describe what a survey is.
Content Standard A:
Write responses on the board. Most students will have taken a
Use appropriate tools
survey or at least seen one. Guide students to discuss what surveys
and techniques to
might ask about, who might administer them, and what the
information might be used for.
gather, analyze, and
interpret data.
2. On the board, write the question, Do you play a sport? Ask only
two or three students for a response to the question and write
their responses on the board.
59
Student Lesson 3
The Science of Healthy Behaviors
Ask
only two or three students in a class of about 30. Ask only
one or two students in smaller classes. This question is purposely
general and should elicit a variety of answers, including, “Yes,” “No,”
“Sometimes,” “Not now,” “I used to,” and “Basketball.” Write each
student’s answer in a separate column.
3. Tell the class that you want to study physical activity patterns in
students. On the basis of this information, ask students to get a
more specific answer by either revising the question or asking a
new question.
Write the new questions on the board below the original question.
Ask the same students who answered the original question these
new questions. Write their answers on the board in the appropriate
column, below their answer to the first question.
Students may suggest asking additional questions such as, Do you
play a team or individual sport?; Which sport do you play?; Do you
participate in a physical activity that is not considered a sport?; or,
How often do you play?
4. Return to the questions on the board. Select the answers from
one student. Ask the class,
• “Do these answers from one person represent how all or most
of the students in the class would respond?” (Does everyone
agree with these answers?)
• “How many people would need to answer the question to
represent how all or most of the students in the class would
respond?”
• “Would the answers represent how all or most of the
students in the school would answer the questions?”
• “Would the answers represent how middle school students in
other schools in the city, state, or country would answer the
questions?”
• “Would the answers represent how students in lower or
higher grades would answer the questions?”
Students will probably realize that one person does not accurately
reflect all students in the class, the school, the community, or in
other grades. After a brief discussion of how many people it would
take to provide an accurate representation, introduce the term
sample size. Sample size is determined by two factors: the size of the population of interest, and how confident you need to be that your
results are representative of that population. Sample size can be
determined by mathematical formulas, which are beyond the scope
of this curriculum. However, consider the following table that relates
population size, confidence level, and sample size.
60
Sample Size
Population Size*
Needed for
30
100
1,000
5,000
10,000
50,000
90 percent
27
73
214
258
265
271
confidence
(90%)
(73%)
(21.0%) (0.05%) (0.03%) (0.01%)
95 percent
28
79
278
357
370
381
confidence
(93%)
(79%)
(28.0%) (0.07%) (0.04%) (0.01%)
99 percent
29
87
399
586
622
655
confidence
(97%)
(87%)
(40.0%) (0.12%) (0.06%) (0.01%)
* Sample size as a percent of population size is in parentheses.
Data in this table demonstrate that the smaller the population, the
larger the percentage of that population the sample size must be to
be a representative sample. Make a transparency of this table if you
believe it would help your students understand sample size.
Introduce the term representative sample when discussing which
other groups may be represented accurately in a class survey. For
example, students will probably recognize that first-graders would
give very different answers from their own. Likewise, college
students would give substantially different answers. Additionally,
middle school students from different parts of the country, as well as
from urban, rural, or suburban areas, would probably give different
answers. Therefore, students need to be aware that a survey provides
information about a specific population that may not be applicable
to other groups. In other words, the group of people participating in
the survey needs to be carefully defined to ensure that the survey
is useful; then, a random sample within that population should be
surveyed to avoid skewing the results.
5. Give each student a copy of Master 3.1, Survey. (If your school
district requires parental permission for students to fill out
surveys, you should have collected the Permission Letters by
now.) Tell the students that they will now participate in a survey
of physical activity behaviors of middle school students.
Students will answer questions about various forms of physical
activity as well as influences on physical activity. Then they compare
their class data with a larger database of all classes using this
curriculum and with data derived from the national Add Health
study in Activity 2.
Students should take the survey in a manner that respects and
preserves their privacy. Their personal data remain anonymous in
further activities. However, students should keep their surveys to
make their own comparisons with data from other sources. As soon
as students complete their surveys, they should either enter their
data in the online database (for the Web version of this activity) or 61
Student Lesson 3
The Science of Healthy Behaviors
tally their information for the class ( print version of this activity). In either case, students should move on to Activity 2 as soon as they
complete their surveys.
Note to teachers: The student survey is part of an extensive national
study of adolescents. In this study, the National Longitudinal Study
of Adolescent Health (or Add Health study), over 20,000 students
in grades 7 through 12 answered a very long survey in school,
followed by three in-home interviews over the next eight years. The
information provided in this curriculum supplement uses responses
from over 6,000 seventh-grade students. The Add Health study uses
a very large sample size and draws from a nationally representative
sample. Data from the Add Health study have been used by
epidemiologists around the country to investigate various aspects of
adolescent behavior and health.
Activity 2: Analyzing the Physical Activity Survey
Results (Or, Who Else Does That?)
For classes using the Web version of this activity:
Note to teachers: You will need to examine your school’s
computer and Web resources to determine the most
effective way to enter data into the database. Can an entire class get
computer access and enter data simultaneously? Can small groups
access a few computers while the remainder of the class is working
on other tasks? One option is to have students fill out the survey on
paper and then have one person enter the data. To protect students’
privacy, remind students not to write their names on the survey.
It will save time to have the computers online and at the correct
URL: http://science.education.nih.gov/supplements/healthy/student.
This is a main menu page from which you and students can access
this activity. Students will need the class code you established for
their class to access the Activity 2—Data Entry and Activity 2—
Analyzing the Survey Results menu pages.
We recommend that the survey and the discussion of the use of
the database be completed during class. Students can then generate
reports during class or, if necessary, from home.
1. Have students open their browser to http://science.education.
nih.gov/supplements/healthy/student and click on the link
“Activity 2—Data Entry.” They should enter the unique class
code you obtained for their class and then enter their survey
data by clicking on the appropriate response for each of the 12
questions.
62
You may want to demonstrate for students how this is done to
ensure that data entry proceeds smoothly and quickly.
2. When student data entry has been completed, divide the class
Content Standard A:
into groups of two to four. Give each student a copy of Master
Mathematics is impor-
3.2, Comparison Guide, and ask students to click on the link to
“Activity 2—Analyzing the Survey Results.”
tant in all aspects of
scientific inquiry.
3. Explain that each group will compare their class’s results with
data from all classes entering survey data and with data from
the Add Health study.
Each group of students will compare one question that has two
possible answers (that is, no or yes questions) and one question that has four or five possible answers (that is, how many times questions).
You may assign the questions or let students select them.
4. Tell students they will be given the number of respondents
to each answer for their class but will have to calculate
the percentage of the total population that that number of
respondents represents and graph the results themselves.
The number of respondents, percentages, and the graphs from
the all-classes database and Add Health database are provided
for students online. Results are presented in table and bar-graph
formats. Students should copy their class’s data onto their copy
of Master 3.2, Comparison Guide, make the calculations for their
class, and draw the corresponding bar graph. Students should
then answer the questions on the master. Students can use colored
pencils to draw the bars on their graph. Make sure students label
the legend on their graph. Students should compare the data
they get from all three data sources. They should also discuss the
reasons for any difference or lack of difference in results among
data sources. Allow approximately 15 minutes for completion of
this step.
Tip from the field test: Be prepared to review how to
calculate percentages.
Note to teachers: The data are provided to students in two forms.
Tables generated for each question include both the actual number
and the percentage of respondents who gave each answer. The all-
classes database includes all classes that have taken the survey as
part of The Science of Healthy Behaviors curriculum supplement and
entered these data online. In the data from the Add Health study,
the total number of respondents differs between questions. This is
because respondents could choose not to answer questions or could
63
Student Lesson 3
The Science of Healthy Behaviors
select answers, such as “not applicable,” that are not available to
students using the survey in this curriculum supplement.
5. Reconvene the class. Refer to Master 3.2, Comparison Guide, and
ask students if they observed a difference between data from
different sources for the same question. Between which data
sources were the differences greatest? Why? Which data set do
the students think is the most accurate (or most representative
of middle school students)?
Students will probably observe differences among the data from the
three sources. Remind students about the concept of sample size.
This should affect their decision about which data set is the most
accurate (or most representative of middle school students).
Note to teachers: Initially, results from all classes entering survey
data may be very similar to results from individual classes. Over
time, however, results from all classes using this supplement will
grow larger and more representative and should become similar to
the results from the Add Health study.
6. In some cases, similar percentages are observed for responses
to the same questions on both data sets, although the numbers
of respondents are very different. Why is this?
Students may observe similar percentages even though the numbers
are very different. This indicates that the smaller samples are
representative. Remind the students of the concepts of sample
size and representative sample if they do not bring them up in the
discussion.
Tip from the field test: Students are familiar with making scientific
measurements in a laboratory. This is a good time to
point out to students that human behavior also can be
measured and studied scientifically.
For classrooms using the print version of this activity:
1. Tally the class data from the individual student
surveys.
Write the number of students responding to each answer of each
question on a transparency of Master 3.1, Survey.
64
2. Divide the class into groups of two to four. Give each group a
copy of Master 3.3, Add Health Study Data, and each student a
copy of Master 3.4, Class and Add Health Study Comparison.
3. Explain that each group will compare their class’s results with
Content Standard A:
data from the Add Health study.
Mathematics is impor-
tant in all aspects of
Each group of students will compare one question that has two
scientific inquiry.
possible answers (that is, no or yes questions) and one question that has four or five possible answers (that is, how many times questions).
You may assign the questions or let the students select them.
Students should copy their class’s data onto their copy of Master 3.4,
Class and Add Health Study Comparison, and answer the questions
about their class’s data on the master. They will have to calculate the
percentages for their class.
Tip from the field test: Be prepared to review how to
calculate percentages.
4. Ask students to copy the Add Health data into the tables on
Master 3.4. Then they will graph the percentages for each data set.
Students can use colored pencils to draw their bars on the graph.
Make sure students label the legend on their graphs. On page 3 of
Master 3.4, students should compare the data from the two data
sources. They should also discuss the reasons for any difference in
results between the two data sources. Allow approximately
15 minutes for students to complete Steps 3 and 4.
Note to teachers: The data are provided to students in two forms.
Tables indicate both the actual number and the percentage of
respondents who gave a particular answer. In the results from the
Add Health study, the total number of respondents differs between
questions. This is because respondents could choose not to answer
questions or could select answers, such as “not applicable,” that
are not available to students using the survey in this curriculum
supplement.
5. Reconvene the class. Refer to Master 3.4, Class and Add Health
Study Comparison, and ask students if they observed a difference
between the data sets from the two sources for the same
question. Why? Which data set do the students think is more
accurate (or more representative of middle school students)?
Students will probably recognize differences between the data from
the two sources. Remind the students about the concept of sample
65
Student Lesson 3
The Science of Healthy Behaviors
size. This should affect their decision about which data set is more
accurate (or more representative).
6. In some cases, similar percentages may be observed for
responses to the same questions on both data sets, although the
numbers of respondents are very different. Why is this?
Students may observe similar percentages even though the numbers
are very different. This indicates that the smaller samples are
representative. Remind students of the concepts of sample size and
representative sample if they do not bring them up in the discussion.
Activity 3: Getting More out of Surveys
For classrooms using the Web version of this activity:
1. Divide the class into groups of three or four again,
and have the groups proceed to the computers.
Remind students that the goals of the survey they took are to
examine physical activity behaviors in middle school students and
to evaluate some influences on those behaviors.
2. Ask students if the summary data that they reviewed in Activity
2 is all the information they could get from the surveys.
Accept a couple of responses quickly. Students may believe that
each question stands alone and the only information that can
be obtained from the survey relates to data for each question
individually.
3. Ask students to suggest ways to get more information about
physical activity behaviors and influences from the survey.
Accept all student responses. Do this quickly.
4. Give students an example of how to get more information from
the survey results. For example, scientists could ask, Do males
play an active sport more times per week than females do?
A large number of questions can be asked. Students could compare
males and females for each behavior. For example, Do males
watch TV or play video games more than females do? Students
can phrase a question that relates any of the behaviors to any of
the influences besides male and female. For example, Do middle
school students who have a physical fitness or recreational center
in their neighborhood exercise more times per week than students
66
who don’t? Asking questions such as these allows us to learn about
relationships that exist between influences and behaviors.
5. Have students proceed to the URL http://science.education.nih.
gov/supplements/