Age Structure Studies
Introduction.
The population of the world is nearly 6 billion and is growing at an ever-increasing pace. Changes are
taking place not only in the number of individuals but in the ages of the individuals who make up our
population. Students will collect data from Internet sources to compare age distributions in their city,
county or state with that of other places in the United States or of other countries. They will construct
and interpret age-structure population pyramids and research reasons for the differences in these
graphs among different countries.
Audience.
This lesson is designed for an introductory Biology course. It could also be adapted for use in a
History, Social Studies, Government, Health or Mathematics class.
Previous Knowledge Needed.
Basic Internet skills. Basic graphing skills. Ability to compute percents.
Materials.
Internet access. "Age-Structure Population Pyramids" overhead. "Age-Structure Pyramids" Worksheet.
Calculators may be used.
Objectives.
To access local and world population data on the Internet.
To learn how to read and construct age-structure population pyramids.
To describe characteristics of a population after examining the age-structure pyramid for a particular
country.
To make and test some conjectures about countries with similar age-structure pyramids.
Procedure.
Introduce the idea of the changing age characteristics of the United States population by discussing the
problem of funding social security into the 21st century. Ask students what they have heard about this
problem and what is causing it.
Show the age-structure overhead on "The Aging in Michigan". Explain how to read this pyramid. Each
horizontal bar represents a 5-year age span. Each vertical line represents 100,000 people. For example,
in 1930 there were about 200,000 20-to-25 year old men and about 200,000 20-to-25 year old women.
In 2030, it is projected that there will be about 350,000 men and 350,000 women in the 20-25 year old
category.
The age-structure pyramid shows that the Michigan population has increased a great deal from 1900.
(Students may estimate the total population in 1900 and 2020 by adding up the numbers in each age
group. In 1900 a rough estimate is 2,400,000; in 2020 a rough estimate is 10,000,000.)
The shape of the pyramid is also very important. Discuss why it is easier to fund social security for a
population pyramid with a shape as in 1900 or 1930 than a pyramid with the 2020 shape. (The 20-65
year olds must support those over 65. In 1930, there would be about 2,700,000 people supporting about
250,000; or 250000/2700000 = 0.0926 = 9.25% retired people would have to be supported. In 2020,
approximately 1,750,000 retirees will need to be supported by 5,400,000 people; 1750000/5400000 =
.324 = 32.4%.)
Ask students for suggestions why the shape of the pyramid has altered from 1900 to 2020. (Better
medical services, nutrition, fewer children in families, better retirement benefits.)
The 1960 shape is also unusual. What historical circumstances could account for the large base and
small "waist" in the 20-30 age group? (During World War II, 1940-45, fewer children were born
because men were at war. Hence 20 years later, in 1960, there would be fewer 20-25 year olds. But
after the war, 1950-1960, couples were able to start families creating the "baby boom".)
After students understand how age-structure pyramids are constructed, they can access population data
on the Internet, create their own pyramid and complete the Age-Structure Worksheet. Age-Structure
Pyramids created by the class may be shared either as a whole class or in small groups. Students
should discuss similarities and differences among their pyramids for the different places they had
chosen in order to complete #7 on the Worksheet.
Evaluation.
See points on the Age-Structure Worksheet.
Teacher Notes.
!!!! Warning !!!! The Web sites given in this lesson may have changed! Before using this lesson with
your students, be sure to check if the sites are still working or if you must find another site. Sometimes
the sites still have the relevant data but you may need to change the directions to access the data.
The STF1A option in the census site does not separate age data by gender. However, the STF3A
option will give age data separated by gender and race. Hence if you need exact figures for age data
with regard to gender, you can check all boxes P14A through P14 J and P15A and P15 B under the
STF3A option. You will get 12 tables (for 6 different race categories and 2 different gender
categories). You will need to add corresponding values in each race category to get total numbers for
men and women.
In you are familiar with Microsoft Word and Excel, you could cut and paste these 12 tables into a
Microsoft Word document. Then highlight just the numerical data by holding down the Alt key while
highlighting the "column" that the numbers are in. You will also need to highlight some periods from
this data. Cut and paste this column of numbers in another Word document. Then use Find under the
Edit button on the top bar to find the periods and replace them with a space (choose Replace All). Next
you can cut this new column of numbers into Excel and use Excel to total the appropriate cells.
If you wish, you could have students access the STF3A site and, instead of making an age-structure
pyramid for the entire population, make age-structure pyramids for two or three different races, then
compare the shapes of these pyramids.
If you need more background about the statistical concepts involved in the lesson, some good sites to
check are:
In order to print out just a copy of the student worksheet, highlight this section, then copy and paste it
into your word processor. You may then revise the worksheet if you wish.
Wisconsin’s Model Academic Standards Addressed
Science:
A12.3. Give examples that show how partial systems, models, and explanations are
used to give quick and reasonable solutions that are accurate enough for basic needs.
A12.4. Construct arguments that show how conflicting models and explanations of
events can start with similar evidence.
A12.5. Show how the ideas and themes of science can be used to make real-life
decisions about careers, work places, life-styles, and use of resources.
B12.3. Relate the major themes of science to human progress in understanding science
and the world.
C12.1. When studying science content, ask questions suggested by current social issues,
scientific literature, and observations of phenomena; build hypotheses that might
answer some of these questions; design possible investigations; and describe results that
might emerge from such investigations.
C12.2. Identify issues from an area of science study, write questions that could be
investigated, review previous research on these questions, and design and conduct
responsible and safe investigations to help answer the questions.
C12.3. Evaluate data collected during an investigation, critique the data-collection
procedures and results, and suggest ways to make any needed improvements.
C12.4. During investigations, choose the best data-collection procedures and materials
available, use them competently and calculate the degree of precision of the resulting
data.
G12.4. Show how a major scientific or technological change has had an impact on
work, leisure, or the home.
H12.6. Evaluate data and sources of information when using scientific information to
make decisions.
Mathematics:
D12.3. Determine measurements indirectly, using estimation, proportional reasoning,
techniques of algebra, geometry and trigonometry, formulas, geometric relationships or
conversion constants.
E12.1 Work with data in the context of real-world situations by formulating hypotheses
that lead to collection and analysis of one- and two-variable data, using technology to
generate displays, summary statistics and presentations.
E12.2. Organize and display data from statistical investigations using frequency
distributions, percentiles, quartiles, deciles, line of best fit or matrices.
E12.3. Interpret and analyze information from organized and displayed data when given
measures of dispersion, reliability or correlation.
Social Studies:
A12.1. Use various types of atlases and appropriate vocabulary to describe the physical
attributes of a place or region, employing such concepts as climate, plate tectonics,
volcanism, and landforms, and to describe the human attributes, employing such
concepts as demographics, birth and death rates, doubling time, emigration, and
immigration.
A12.2. Analyze information generated from a computer about a place, including
statistical sources, aerial and satellite images, and three-dimensional models.
A12.4. Analyze the short-term and long-term effects that major changes in population in
various parts of the world have had or might have on the environment.
B12.9. Select significant changes caused by technology, industrialization, urbanization,
and population growth, and analyze the effects of these changes in the United States and
the world.
E12.14. Use the research procedures and skills of the behavioral sciences (such as
gathering, organizing, and interpreting data from several sources) to develop an
informed position on an issue.
Activity Sheets.
The Aging in Michigan
Figure 2. Percent Distribution of Population by Age and Sex:
Michigan, 1900-2020
Age-Structure Pyramids Worksheet
Name ________________________
1. (5 points) Access the site http://www.census.gov/cgi-bin/gazetteer Type in a city, county, state or
zip code to search for, then click Search. You may get a list of several areas with that name; decide
which area is the one you are interested in. Under Lookup 1990 Census under that area, click on
STF1A tables. Click P1 persons, P5 Sex and P11 Age. Click the HTML format, go to the top of the
page, and then click Submit.
2. (5 points each). Since this data is not separated according to gender, estimate that about half of the
population will be men and half women. What percent of your population are men? women?
a. Total Population
__________
Total Men ___________
Percent Men ___________
Total Women ___________
Percent Women ___________
b. Is it a reasonable assumption to estimate that about half of your population are men and half are
women? Explain why.
c. We will also estimate that about half of the population in each age group are men and half are
women. Is this a reasonable assumption? If not, for which age groups would this assumption probably
not be true? Explain why.
3. (15 points) Add up the number of individuals in the table you obtain for each age group:
Age (years)
Total Number of Persons
½ Total Number of Persons
0-4
_______________
_______________
5-9
_______________
_______________
10-14
_______________
_______________
15-19
_______________
_______________
20-24
_______________
_______________
25-29
_______________
_______________
30-34
_______________
_______________
35-39
_______________
_______________
40-44
_______________
_______________
45-49
_______________
_______________
50-54
_______________
_______________
55-59
_______________
_______________
60-64
_______________
_______________
65-69
_______________
_______________
70-74
_______________
_______________
75-79
_______________
_______________
80-84
_______________
_______________
85+
_______________
_______________
4. (25 points) Make an age-structure pyramid with your data on the attached graph paper.
5. (15 points) Access the site http://www.census.gov/ftp/pub/ipc/www/idbpyr.html Find three countries
in different parts of the world and print out their age-structure pyramids.
6. (15 points) Compare and contrast these three countries using their age-structure pyramids. You may
want to find out some other information about these countries to give good explanations why these
age-structure pyramids differ.
7. (10 points) Compare the age-structure pyramid you created with those of other students in the class.
Do they have about the same shape? If not, what could account for the differences in their shapes?
----------------------------------------------------------------------------------------------------------------------------- ---------------------------------------------
Age-Structure Pyramid
For (Country)_____________________________
AGE
Male
Female
__85+ ____________________________________|___________________________________
80-84 ____________________________________|___________________________________
75-79 ____________________________________|___________________________________
70-74 ____________________________________|___________________________________
65-69 ____________________________________|___________________________________
60-64 ____________________________________|___________________________________
55-59 ____________________________________|___________________________________
50-54 ____________________________________|___________________________________
45-49 ____________________________________|___________________________________
40-44 ____________________________________|___________________________________
35-39 ____________________________________|___________________________________
30-34 ____________________________________|___________________________________
25-29 ____________________________________|___________________________________
20-24 ____________________________________|___________________________________
15-19 ____________________________________|___________________________________
10-14 ____________________________________|___________________________________
__5-9 ____________________________________|___________________________________
__0-4 ____________________________________|___________________________________
…………|………|………|………|………|………0………|………|………|………|………|…………
Population
-------------------------------------------------------------------------------------------------------------------
Age-Structure Pyramids Worksheet (Answers)
1. (5 points) Access the site http://www.census.gov/cgi-bin/gazetteer Type in a city, county, state or
zip code to search for, then click Search. You may get a list of several areas with that name; decide
which area is the one you are interested in. Under Lookup 1990 Census under that area, click on
STF1A tables. Click P1 persons, P5 Sex and P11 Age. Click the HTML format, go to the top of the
page, and then click Submit.
Madison, WI was chosen
2. (5 points each). Since this data is not separated according to gender, estimate that about half of the
population will be men and half women. What percent of your population are men? women?
a. Total Population _191262_
Total Men _93179_
Percent Men _48.7%_
Total Women _98083_
Percent Women _ 51.3% _
b. Is it a reasonable assumption to estimate that about half of your population are men and half are
women? Explain why.
Yes, since 48.7% and 51.3% are very close.
c. We will also estimate that about half of the population in each age group are men and half are
women. Is this a reasonable assumption? If not, for which age groups would this assumption probably
not be true? Explain why.
No, because in the other pyramids we looked at, there were a lot more older women than men in the
age groups over 60.
3. (15 points) Add up the number of individuals in the table you obtain for each age group:
Age (years)
Total Number of
Persons
½ Total Number of Persons
0-4
11,863
5,931
5-9
10,387
5,193
10-14
8,527
4,263
15-19
16,297
8,148
20-24
30,670
15,335
25-29
20,777
10,388
30-34
18,220
9,110
35-39
16,257
8,128
40-44
13,124
6,562
45-49
8,864
4,432
50-54
6,605
3,302
55-59
5,917
2,958
60-64
5,923
2,961
65-69
5,458
2,729
70-74
4,354
2,177
75-79
3,309
1,699
80-84
2,408
1,204
85+
2,211
1,105
4. (25 points) Make an age-structure pyramid with your data on the attached graph paper.
5. (15 points) Access the site http://www.census.gov/ftp/pub/ipc/www/idbpyr.html Find three countries
in different parts of the world and print out their age-structure pyramids.
6. (15 points) Compare and contrast these three countries using their age-structure pyramids. You may
want to find out some other information about these countries to give good explanations why these
age-structure pyramids differ.
Access the international census site http://www.census.gov/ipc/www/idbsum.html and obtain more
population data about these three countries.
Afghanistan
Iceland
Japan
1998
2010
1998
2010
1998
2010
Births per 1,000 people
42
37
15
12
10
9
Deaths per 1,000 people
17
13
7
8
8
10
Rate of natural increase
(percent)
2.5
2.4
0.8
0.5
0.2
-0.1
Annual rate of growth
(percent)
4.2
2.4
0.5
0.3
0.2
-0.1
Life expectancy at birth
(years)
46.8
53.1
78.8
80.1
80.0
81.1
Infant deaths per 1,000 live
births
144
107
5
5
4
4
Totality fertility rate (per
woman)
6.0
5.1
2.0
1.8
1.5
1.5
Japan's pyramid is smaller on the bottom because it's annual rate of growth is very small and is
projected to be negative in 2010. Afghanistan's pyramid is very large on the bottom because its annual
rate of growth is large; also the death rate is much larger and life expectancy much smaller.
7. (10 points) Compare the age-structure pyramid you created with those of other students in the class.
Do they have about the same shape? If not, what could account for the differences in their shapes?
Because of the University of Wisconsin in Madison, which enrolls a large number of both
undergraduate and graduate students, the 18-35 year old age groups will have a much greater
proportion of individuals than other cities. UWM students account for the wide spread in these age
groups.
---------------------------------------------------------------------------------------------------------------------
Age-Structure Pyramid
For _________Madison, WI___________
AGE
Male
Female
__85+ __________________________________**|**_________________________________
80-84 _________________________________***|***________________________________
75-79 ________________________________****|****_______________________________
70-74 _______________________________*****|*****______________________________
65-69 ______________________________******|******_____________________________
60-64 _____________________________*******|*******____________________________
55-59 _____________________________*******|*******____________________________
50-54 ____________________________********|********___________________________
45-49 __________________________**********|**********_________________________
40-44 ______________________**************|**************_____________________
35-39 ___________________*****************|*****************__________________
30-34 ________________********************|********************_______________
25-29 ______________**********************|**********************_____________
20-24 ____********************************|********************************___
15-19 ___________________*****************|*****************__________________
10-14 ___________________________*********|*********__________________________
__5-9 _________________________***********|***********________________________
__0-4 _______________________*************|*************______________________
…….15………12………9………6………3………0………3………6………9………12……15……
Population in Thousands
1990 US Census Data
Database: C90STF1A
Summary Level: State--Place
Madison city: FIPS.STATE=55,
FIPS.PLACE90=48000
PERSONS
Universe: Persons
Total..................................................................191262
SEX
Universe: Persons
Male....................................................................93179
Female..................................................................98083
AGE
Universe: Persons
Under 1 year.............................................................2190
1 and 2 years............................................................5043
3 and 4 years............................................................4630
5 years..................................................................2247
6 years..................................................................2141
7 to 9 years.............................................................5999
10 and 11 years..........................................................3593
12 and 13 years..........................................................3343
14 years.................................................................1591
15 years.................................................................1632
16 years.................................................................1544
17 years.................................................................1702
18 years.................................................................4025
19 years.................................................................7394
20 years.................................................................7653
21 years.................................................................7267
22 to 24 years..........................................................15750
25 to 29 years..........................................................20777
30 to 34 years..........................................................18220
35 to 39 years..........................................................16257
40 to 44 years..........................................................13124
45 to 49 years...........................................................8864
50 to 54 years...........................................................6605
55 to 59 years...........................................................5917
60 and 61 years..........................................................2335
62 to 64 years...........................................................3588
65 to 69 years...........................................................5459
70 to 74 years...........................................................4354
75 to 79 years...........................................................3399
80 to 84 years...........................................................2408
85 years and over........................................................2211
1990 US Census Data
Database: C90STF3A
Summary Level: State--Place
Madison city: FIPS.STATE=55,
FIPS.PLACE90=48000
RACE BY SEX BY AGE
Universe: White males
Under 1 year..............................................................873
1 and 2 years............................................................2172
3 and 4 years............................................................1868
5 years...................................................................968
6 years..................................................................1033
7 to 9 years.............................................................2699
10 and 11 years..........................................................1586
12 and 13 years..........................................................1363
14 years..................................................................713
15 years..................................................................619
16 years..................................................................691
17 years..................................................................809
18 years.................................................................1767
19 years.................................................................3229
20 years.................................................................3523
21 years.................................................................3590
22 to 24 years...........................................................7385
25 to 29 years...........................................................9419
30 to 34 years...........................................................7866
35 to 39 years...........................................................7322
40 to 44 years...........................................................5950
45 to 49 years...........................................................4063
50 to 54 years...........................................................2930
55 to 59 years...........................................................2698
60 and 61 years..........................................................1004
62 to 64 years...........................................................1688
65 to 69 years...........................................................2238
70 to 74 years...........................................................1832
75 to 79 years...........................................................1216
80 to 84 years............................................................734
85 years and over.........................................................471
RACE BY SEX BY AGE
Universe: White females
Under 1 year..............................................................840
1 and 2 years............................................................2107
3 and 4 years............................................................1957
5 years...................................................................855
6 years...................................................................886
7 to 9 years.............................................................2445
10 and 11 years..........................................................1417
12 and 13 years..........................................................1342
14 years..................................................................679
15 years..................................................................629
16 years..................................................................586
17 years..................................................................747
18 years.................................................................1828
19 years.................................................................3537
20 years.................................................................3437
21 years.................................................................3573
22 to 24 years...........................................................6847
25 to 29 years...........................................................8917
30 to 34 years...........................................................8261
35 to 39 years...........................................................7675
40 to 44 years...........................................................5995
45 to 49 years...........................................................4640
50 to 54 years...........................................................3245
55 to 59 years...........................................................3040
60 and 61 years..........................................................1221
62 to 64 years...........................................................1947
65 to 69 years...........................................................2544
70 to 74 years...........................................................2753
75 to 79 years...........................................................2194
80 to 84 years...........................................................1717
85 years and over........................................................1510
RACE BY SEX BY AGE
Universe: Black males
Under 1 year..............................................................123
1 and 2 years.............................................................289
3 and 4 years.............................................................249
5 years...................................................................106
6 years...................................................................100
7 to 9 years..............................................................265
10 and 11 years...........................................................150
12 and 13 years...........................................................156
14 years...................................................................81
15 years...................................................................80
16 years...................................................................43
17 years...................................................................40
18 years...................................................................71
19 years..................................................................144
20 years...................................................................50
21 years...................................................................61
22 to 24 years............................................................181
25
30
35
40
45
50
55
60
62
65
70
75
80
85
to 29 years............................................................519
to 34 years............................................................448
to 39 years............................................................417
to 44 years............................................................330
to 49 years............................................................171
to 54 years.............................................................88
to 59 years............................................................130
and 61 years.............................................................6
to 64 years.............................................................23
to 69 years.............................................................54
to 74 years.............................................................21
to 79 years.............................................................11
to 84 years..............................................................0
years and over...........................................................0
Etc.