D2.Soc.15.9-12: Identifying Common Patterns of Social Inequality
In plain English: D2.Soc.15.9-12 is the C3 Framework sociology indicator for grades 9-12 that asks students to identify common patterns of social inequality. Students read official data to find regular differences in income, poverty and earnings by income group, education, age, sex, and race and Hispanic origin, and test a 1927 definition of social stratification against 2025 Census figures.
Identify common patterns of social inequality.
C3 Framework for Social Studies (NCSS) · Dimension 2: Applying Disciplinary Concepts and Tools · Discipline: Sociology · Stratification and Inequality · Official standard
D2.Soc.15.9-12 asks students to identify common patterns of social inequality. Social inequality means that the things a society values, such as income, wealth, education, health, power and respect, are shared out unevenly among its members. A pattern of inequality is a difference that shows up regularly between groups of people, not one person's good or bad luck: for example, a gap between the income of households at the top and at the bottom, or between the poverty rates of children and adults. Sociologists call a lasting ranking of groups into higher and lower layers social stratification.
The lesson pairs a founding definition with current official data. Pitirim A. Sorokin's 1927 book Social Mobility (Source 1) defines stratification and names the main forms it takes. The U.S. Census Bureau's September 2026 release on income and poverty in 2025 (Source 2) and four Census historical tables give the patterns by income group, education, race and Hispanic origin, age and sex. A draft report with deliberate errors (Source 3) teaches students to state patterns accurately. The page identifies patterns only; explaining their causes and effects belongs to D2.Soc.16.9-12 and D2.Soc.17.9-12.
Learning Objectives
By the end of this lesson, students will be able to:
Define social inequality, social stratification and a pattern of inequality, using Sorokin's 1927 definition
Identify patterns of inequality by income group, education, age, sex, and race and Hispanic origin in official Census data
Compute and compare shares, ratios and percentage-point changes, and tell percentage points from percents
State a pattern accurately, without overgeneralizing or claiming a cause the data do not show
Prior Knowledge Required
Students should already be comfortable with:
How in-group and out-group membership shapes life chances D2.Soc.14.9-12
"Imagine all the income earned by every household in the country as one pie, cut into five slices for five equal-sized groups of households, from lowest income to highest. If the pie were shared equally, what share would each slice get? Predict the share the top slice actually gets."
Equal shares would be 100 / 5 = 20 percent each. Record the class's predictions for the top fifth, then reveal Table A in Direct Instruction. The gap between 20 percent and the real share is the lesson's first pattern.
Direct Instruction20 minutes
Key terms. A fifth (or quintile) is one of five equal-sized groups of households ranked by income. A median is the middle value: half of the households have more, half less. A percentage point is the unit for the difference between two percents: going from 40 percent to 50 percent is a rise of 10 percentage points, which is a rise of 25 percent. The official poverty rate is the percent of people whose family's pretax money income is below a federal threshold that varies with family size and makeup, as the Census Bureau's release explains.
Reading 1. Pitirim A. Sorokin's Social Mobility was published in New York in 1927; the book's preface is signed from Minneapolis. Strata (singular stratum) are layers, hierarchically superposed means stacked in ranks one above another, and privations are hardships or lacks. Read for one question: what, according to Sorokin, is the "very essence" of stratification, and what are its main forms?
1Social stratification means the differentiation of a given population into hierarchically superposed classes. It is manifested in the existence of upper and lower social layers. Its basis and very essence consist in an unequal distribution of rights and privileges, duties and responsibilities, social values and privations, social power and influences among the members of a society. Concrete forms of social stratification are different and numerous. If the economic status of the members of a society is unequal, if among them there are both wealthy and poor, the society is economically stratified, regardless of whether its organization is communistic or capitalistic, whether in its constitution it is styled “the society of equal individuals” or not. Labels, signboards and “speech reactions” cannot change nor obliterate the real fact of the economic inequality manifested in the differences of incomes, economic standards, and in the existence of the rich and the poor strata. If the social ranks within a group are hierarchically superposed with respect to their authority and prestige, their honors and titles; if there are the rulers and the ruled, then whatever are their names (monarchs, executives, masters, bosses), these things mean that the group is politically stratified, regardless of what is written in its constitution or proclaimed in its declarations. If the members of a society are differentiated into various occupational groups, and some of the occupations are regarded as more honorable than others, if the members of an occupational group are divided into bosses of different authority and into members who are subordinated to the bosses, the group is occupationally stratified, independently of the fact whether the bosses are elected or appointed, whether their position is acquired by social inheritance or personal achievement.
2Concrete forms of social stratification are numerous. The majority of them may, however, be reduced to three principal classes: the economic, the political, and the occupational stratification. As a general rule, these forms are closely intercorrelated with each other. Usually, those who occupy the upper strata in one respect happen to be in the upper strata also in other respects, and vice versa. The men who dwell in the upper economic layers happen also to be in the upper political and occupational strata. The poor, as a rule, are politically disfranchised and dwell in the lowest strata of the occupational hierarchy. Such is the general rule, though there are, however, many exceptions to it. Not always are the wealthiest men at the apex of the political or occupational pyramid; and not always are the poor men the lowest in the political or the occupational gradations. This means that the intercorrelation among the three forms of stratification is far from being perfect; the strata of each form do not coincide completely with one another. There is always a certain degree of overlapping among them. This fact does not permit us to analyze in a summary way all three fundamental forms of social stratification. For the sake of a greater accuracy each form has to be studied separately. [...]
Pitirim A. Sorokin, Source 1: Sorokin defines social stratification and its three main forms (1927) (1927). Public domain (published 1927). Source text.
Table A. Share of all household income received by each fifth of households, 1967 and 2025 (percent). U.S. Census Bureau, Historical Income Table H-2
Year
Lowest fifth
Second fifth
Middle fifth
Fourth fifth
Highest fifth
Top 5 percent
1967
4.0
10.8
17.3
24.2
43.6
17.2
2025
3.0
8.2
13.9
22.5
52.4
23.5
A pattern, not a single case: Table A
Use Table A to state the main pattern in how income was shared among households in 2025.
Result: If income were shared equally, each fifth would receive 20 percent. In 2025 the highest fifth received 52.4 percent and the lowest fifth 3.0 percent. The middle and fourth fifths together received 13.9 + 22.5 = 36.4 percent, less than the highest fifth alone. That is a pattern across about 137 million households, not one family's story.
Change over time: Table A, highest fifth
How did the highest fifth's share change from 1967 to 2025? Give the change in percentage points and as a percent.
Result: 52.4 - 43.6 = 8.8 percentage points. As a percent of the 1967 share, 8.8 / 43.6 is about 0.20, a rise of about 20 percent. Saying "the share rose 8.8 percent" would be an error: the rise was 8.8 percentage points. The Census Bureau's footnotes to Table H-2 mark several changes in survey methods since 1967, so long-run changes are more trustworthy than small year-to-year ones.
Economic stratification: Source 1, paragraph 1
Which of Sorokin's forms of stratification does Table A measure, and why does his definition fit it?
Result: Table A measures economic stratification. Sorokin says stratification "is manifested in the existence of upper and lower social layers," and he names economic inequality "manifested in the differences of incomes." Table A shows exactly those differences of income, ranked in five layers from lowest to highest.
Sex: Source 2, paragraphs 9-10
State the 2025 pattern in earnings for women and men, and what the measure compares.
Result: The female-to-male earnings ratio "compares the median earnings of women and men, both working full-time, year-round." In 2025 it was 83.9 percent: the median woman working full-time, year-round earned about 84 cents for each dollar earned by the median man.
Diagram 1 draws Table A to scale. Close the segment: Sorokin wrote in 1927; the table starts in 1967. Is the pattern he defined still visible? Students should see that the unequal distribution of income he describes appears in both years, while its size has changed.
Guided Practice15 minutes
Work through Table B together. It ranks households by the education of the householder (in Census tables, usually the person in whose name the home is owned or rented). Ask students to write one pattern sentence using the frame: "In [year], [group] had [measure] of [value], compared with [value] for [group]."
Table B. Median household income by the householder's education, householders 25 and older, 2025. U.S. Census Bureau, Historical Income Table H-13
Highest education of householder
Median household income
Less than 9th grade
$36,360
9th to 12th grade, no diploma
$37,630
High school graduate
$60,790
Some college, no degree
$76,160
Associate degree
$85,000
Bachelor's degree
$127,100
Master's degree
$149,100
Professional degree
$190,400
Doctorate
$176,500
Read the trend. How does median household income change as education rises? (It rises at each step from "Less than 9th grade" through "Professional degree.")
Compute a gap. How much higher is the median for a master's degree than for an associate degree? ($149,100 - $85,000 = $64,100.)
Check for exceptions. Is there any step where the median does not rise? Hold the answer for Activity 2.
What the table cannot show. The table compares groups; it does not follow the same people over time, and it does not hold age, place or field of work constant. Older householders, for example, have had more years to raise their earnings. A pattern sentence states the difference; it does not claim that the degree alone caused it.
Independent Practice15 minutes
Students read Source 2 on their own, then study Tables C and D. Source 2 is the Census Bureau's press release; its figures come from a survey of households (the CPS ASEC), so each figure is an estimate with a margin of error. In Table C, "alone" means people who reported one race; Hispanic origin is asked separately, so Hispanic householders may be of any race. Each median hides a wide range of incomes within every group. Table C also leaves groups out: Table H-5 has no rows for American Indian and Alaska Native or Native Hawaiian and Other Pacific Islander householders, and its "alone or in combination" rows, which count people who reported more than one race, are not shown here. Estimates for groups with fewer households in the survey have larger margins of error.
1SEPT. 15, 2026 — The U.S. Census Bureau today announced that real median household income was $87,460 in 2025, the highest on record dating back to 1967.
[...]
2Although the 2026 CPS ASEC was collected using standard procedures, response rates are still lower than they were before the pandemic. The weighted response rate for the 2026 CPS ASEC was 61.3% compared to 62.0% for the previous year.
3As response rates decline, the risk of bias increases. To reduce the bias, the CPS ASEC program includes adjustments to survey weights for nonresponse and controls them to population totals to ensure the CPS ASEC results are representative of the U.S. population.
[...]
4Median household income was $87,460 in 2025, an increase of 2.6% from the 2024 estimate of $85,210. Household income in 2025 was the highest on record dating back to 1967.
5Between 2024 and 2025, median income increased by 3.0% for White households, 2.9% for non-Hispanic White households, and 4.8% for Black households. Median income did not change significantly for Asian or Hispanic households. The differences among the 2024-2025 percent changes in median household income for all race and ethnicity groups were not statistically significant.
6Income inequality as measured by the Gini index was not significantly different between 2024 and 2025.
7Household income at the 90th percentile increased 1.7% but did not significantly change at the 10th percentile between 2024 and 2025.
[...]
8Among full-time, year-round workers, median earnings increased 3.2% for women but did not change significantly for men between 2024 and 2025.
[...]
9The female-to-male earnings ratio compares the median earnings of women and men, both working full-time, year-round.
10For full-time, year-round workers, the female-to-male earnings ratio in 2025 increased to 83.9% from 80.6% in 2024.
[...]
11In 2025, the official poverty rate fell 0.5 percentage points to 10.2%. There were 34.5 million people in poverty in 2025.
12The official poverty rate for children fell to a historic low of 13.4% in 2025.
13Between 2024 and 2025, the official poverty rate for Hispanic individuals decreased to a historic low of 13.9%.
[...]
14Social Security continues to be the largest antipoverty program, moving 28.8 million individuals out of SPM poverty in 2025.
[...]
15The CPS ASEC is subject to sampling and nonsampling errors. All comparisons made here and in each respective report have been tested and found to be statistically significant at the 90% confidence level, unless otherwise noted.
U.S. Census Bureau, Source 2: U.S. Census Bureau, income and poverty in 2025 (press release, September 15, 2026) (2026). US government work (17 U.S.C. 105). Source text.
Table C. Median household income by race and Hispanic origin of householder, 2025. U.S. Census Bureau, Historical Income Table H-5
Householder
Median household income
All households
$87,460
Asian alone
$126,300
White alone, not Hispanic
$96,710
Hispanic (of any race)
$73,260
Black alone
$59,980
Table D. Percent of people below the official poverty line, by age, 1959 and 2025. U.S. Census Bureau, Historical Poverty Table 3
Age group
1959
2025
Under 18
27.3
13.4
18 to 64
17.0
9.2
65 and older
35.2
9.8
1SVHS-written sample with deliberate errors, for critique. Draft report: "Patterns of Inequality in the United States, 2025."
2In 2025 the richest fifth of households received 52.4 percent of all household income, so the richest fifth earned about 52 percent more than everyone else put together.
3Education pays off for everyone. Each higher degree in the Census table brings a higher median household income, all the way up to the doctorate.
4Between 2024 and 2025, median income rose 4.8 percent for Black households but only 3.0 percent for White households, so the Census Bureau has shown that the income gap between Black and White households is closing fast.
5Poverty among people 65 and older fell from 35.2 percent in 1959 to 9.8 percent in 2025. This proves that older Americans no longer face any inequality.
6Among people who work full-time, year-round, women's median earnings were 83.9 percent of men's in 2025, up from 80.6 percent in 2024.
SVHS (sample interpretation with deliberate errors), Source 3: A draft report to critique (SVHS-written sample with deliberate errors) (2026). Original passage written for this page.
Source 3, the last reading above, is a draft report for Activity 3. Task: write one accurate pattern sentence for each of Tables C and D and one for Source 2, paragraph 13, citing the table or paragraph. Under each sentence, write one thing the data do not tell you. Diagram 2 draws Table D to scale.
Closure5-10 minutes
Exit ticket: "Name two patterns of inequality from today's data, each with a number and its source. Then explain the difference between a percentage point and a percent."
Teacher notes. (1) The lesson identifies patterns; it does not explain or rank their causes, which D2.Soc.16.9-12 and D2.Soc.17.9-12 take up. Researchers and the public disagree about the causes and about what, if anything, should be done; keep the discussion on what the data show, and present more than one explanation when students raise causes. (2) Patterns by race and Hispanic origin describe group medians from Census categories, not individuals, and every group includes households at every income level. (3) Sorokin uses "the men" and "the poor men" for people in general, as was usual in 1927; his phrase "communistic or capitalistic" refers to forms of economic organization. (4) Census figures are survey estimates. Source 2, paragraph 15 says comparisons in the release were tested at the 90 percent confidence level, and paragraphs 2-3 note lower response rates. (5) Source 3 is written for this page with deliberate errors; Activity 3 uses it. (6) No task asks students about their own family's income or circumstances.
Differentiation Strategies
For Struggling Students
Give the pattern-sentence frame with the table name and the first group filled in, and have students complete the values and the comparison
Before Table A, model the 20-percent equal share with five paper strips of equal length, then cut and tape strips to the real shares
Provide a two-column chart, Pattern and What the data do not show, with one row completed as a model
For Advanced Students
Read the rest of Sorokin's section 2 in the source file and summarize why he says the three forms must be studied separately
Find Table H-2 on the Census site and identify one decade in which the highest fifth's share rose fastest; note the footnotes on method changes
Compare the official poverty measure with the Supplemental Poverty Measure described in Source 2 and explain why the two can show different patterns
Assessment Guidance
What to Look For
Strong answers state each pattern with a group comparison, a number and a source (for example, "in 2025 the highest fifth of households received 52.4 percent of income, the lowest fifth 3.0 percent, Table A"), use percentage points and percents correctly, and say what the data do not show. Watch for students who describe one person's case as a pattern, who read a share as a "percent more," who treat a change that the Census Bureau did not find statistically significant as real, or who claim a cause from a table of group differences. Full-credit work describes groups accurately and respectfully and notes that every group includes a wide range of incomes.
02
Classroom Activities
3 Activities
1
Pattern Sentences: Saying Exactly What the Data Show
15 minPairs
Pairs write three pattern sentences from Table A and Diagram 1, using the frame from Guided Practice, then trade with another pair. The other pair checks each sentence against four tests: it compares groups, gives a number, names the source, and claims no cause.
Sentences to Write
One sentence comparing the lowest and highest fifths in 2025.
One sentence on how the second fifth's share changed from 1967 to 2025, in percentage points.
One sentence on how the fourth fifth's share changed from 1967 to 2025, in percentage points.
Model Sentences
(1) In 2025 the highest fifth of households received 52.4 percent of all household income, compared with 3.0 percent for the lowest fifth (Table A). (2) The second fifth's share fell from 10.8 percent in 1967 to 8.2 percent in 2025, a drop of 2.6 percentage points (Table A). (3) The fourth fifth's share fell from 24.2 percent in 1967 to 22.5 percent in 2025, a drop of 1.7 percentage points (Table A). Each sentence compares groups, gives numbers, names the table and claims no cause.
Discussion
Which test did the sentences you checked fail most often? Ask pairs to rewrite one failed sentence so that it passes all four tests.
2
Testing Sorokin: Does a High Rank in One Respect Match a High Rank in Another?
20 minGroups of 3
In Source 1, paragraph 2, Sorokin claims that the forms of stratification are "closely intercorrelated" as a general rule, with "many exceptions." Groups test the part of the claim that today's tables can reach, using Table B, in a three-row evidence chart: what supports the claim, what is an exception, and what the tables cannot test.
The Evidence Chart
Row 1, Supports: evidence that people ranked higher in one respect tend to rank higher in another. Row 2, Exception: one place where the ranking breaks. Row 3, Cannot test: one part of Sorokin's claim that none of the tables on this page measures.
Answer Key
Supports: if education is taken as a rough stand-in for occupational rank (an assumption, since Table B does not report occupations), Table B shows median household income rising with education from $36,360 (less than 9th grade) to $190,400 (professional degree), so the two kinds of rank tend to go together. Exception: the median for a doctorate ($176,500) is below the median for a professional degree ($190,400), so the ranking is not perfect, which fits Sorokin's "many exceptions." Cannot test: political stratification (who rules and who is ruled), since no table here measures power or authority; and medians cannot show whether the same individuals rank high on every measure.
Step 2: Discussion
Sorokin also wrote that "the poor, as a rule, are politically disfranchised." What kind of data would a researcher need to test that claim today? Groups list two kinds of records, on paper only.
3
Critique the Draft
15 minGroups of 4
Source 3 is a short draft report written for this page with deliberate errors. Groups check each of its five claims (paragraphs 2-6) against Tables A-D and Source 2, mark each claim accurate or inaccurate, and rewrite every inaccurate one so that it states the pattern correctly.
Source 3
Each group reads Source 3, printed in Independent Practice, and uses the critique sheet: claim, verdict, evidence (with table or paragraph), corrected sentence.
Answer Key
Paragraph 2 is inaccurate: a share is not a comparison. The highest fifth received 52.4 percent and the other four fifths 47.6 percent together, so the top fifth received about 10 percent more than all the others combined, not 52 percent more. Paragraph 3 is inaccurate: the doctorate median ($176,500) is lower than the professional-degree median ($190,400), and a median cannot show what happens to "everyone." Paragraph 4 is inaccurate: Source 2, paragraph 5 says "The differences among the 2024-2025 percent changes in median household income for all race and ethnicity groups were not statistically significant," and one year cannot show a trend. Paragraph 5 is inaccurate: 9.8 percent of people 65 and older were still below the poverty line in 2025, and one measure cannot show the absence of "any inequality." Paragraph 6 is accurate (Source 2, paragraph 10). Four claims need rewriting, one is correct.
Variation
Have each group write one new claim of its own from Table C or D with a deliberate error, then trade with another group to find and fix it.
03
Diagrams & Visual Aids
2 diagrams
Diagram 1: How Household Income Was Shared, 1967 and 2025
Drawn to scale from Table A (U.S. Census Bureau, Historical Income Table H-2). The dashed line marks the 20 percent each fifth would receive if income were shared equally. Survey methods changed several times between the two years, as the table's footnotes record.
Diagram 2: Poverty Rates by Age, 1959 and 2025
Drawn to scale from Table D (U.S. Census Bureau, Historical Poverty Table 3), official poverty measure. Each line joins one age group's 1959 rate (light dot) to its 2025 rate (dark dot).
04
Homework Assignment
~30 min
Homework: Reading the Patterns
Directions: Source 1 and Table A are printed in Direct Instruction, Table B in Guided Practice, and Source 2, Tables C and D and Source 3 in Independent Practice. Cite the table or the source and paragraph for every number you use. Problem 5 asks you to plan on paper only: do not survey anyone.
Part 1: Reading the Sources (Problems 1-3)
Sorokin says a group is occupationally stratified "independently of the fact whether the bosses are elected or appointed, whether their position is acquired by social inheritance or personal achievement" (Source 1, paragraph 1). Explain what he means in 2-3 sentences, then give an invented example of a workplace where the bosses are elected but the group is still stratified.
Use Table A. Compute the combined share of income received by the three middle fifths in 1967 and in 2025, and the change in percentage points. Write one pattern sentence about the result.
Source 2, paragraph 14 says Social Security moved 28.8 million people out of poverty under the Supplemental Poverty Measure in 2025. Using Table D, describe the change in poverty for people 65 and older since 1959, and explain why the Social Security figure is evidence about a program's effect on the pattern rather than a description of the pattern itself.
Part 2: Using the Concepts (Problems 4-6)
Invented data: in the invented county of Larkin, the poverty rate is 8 percent in the county seat, 15 percent in the farm townships and 21 percent on the county's two islands, and the median household income is $78,000, $54,000 and $41,000 in the same three places. Identify two patterns, compute the gap in poverty rates between the islands and the county seat in percentage points, and name one thing the data do not tell you.
On paper only, plan how a researcher could check whether the education pattern in Table B still holds when householders of the same age are compared. Say what data you would need and which groups you would compare.
Sorokin writes that labels such as "the society of equal individuals" cannot "change nor obliterate the real fact of the economic inequality" (Source 1, paragraph 1). Write a paragraph explaining the difference between equality in law and equality in the distribution of income, using one table from this lesson as evidence. Do not argue for any policy; explain the distinction.
Rubric
Criterion
Full Credit (2 pts)
Partial Credit (1 pt)
No Credit (0 pts)
Pattern statements
Each pattern compares groups, gives a number and names the source
Patterns stated but one lacks a comparison, number or source
Patterns missing or stated as single cases
Computation
Problems 2 and 4 are correct, with percentage points and percents used correctly
One computing or unit error
Several errors
Limits of the data
Names what the data do not show and avoids claiming causes
Limits mentioned vaguely
A cause is claimed from group differences
Reasoning
Problem 5 is a workable plan on paper; Problem 6 explains the distinction with evidence and stays neutral
Plan or explanation incomplete
Plan or explanation missing
05
Quiz: 20 Questions
Interactive, with answers
Instructions
Source 1 and Table A are printed in Direct Instruction, Table B in Guided Practice, and Source 2 with Tables C and D in Independent Practice. Source 1 is used in Questions 1-5, 14, 15 and 20; Source 2 in Questions 6-8 and 19; Tables A-D in Questions 9-13 and 15-18. Questions 7, 14 and 20 use invented examples. Questions 1-14 are multiple choice; 15-20 are short answer.
Multiple choice: pick an option to check it. Short answer: write your answer, then reveal the model answer.
0 of 20 answered · 0 correct
Question 1 of 20 · Multiple Choice
According to Source 1, paragraph 1, what is the "basis and very essence" of social stratification?
Answer: B
Sorokin: "Its basis and very essence consist in an unequal distribution of rights and privileges, duties and responsibilities, social values and privations, social power and influences." C contradicts him: he says stratification exists "regardless of what is written in its constitution." A and D are not in the passage.
Question 2 of 20 · Multiple Choice
According to Source 1, paragraph 2, into which three principal classes can most forms of stratification be reduced?
Answer: A
"The majority of them may, however, be reduced to three principal classes: the economic, the political, and the occupational stratification." B, C and D are other ways of dividing a society, but they are not the three forms Sorokin names.
Question 3 of 20 · Multiple Choice
According to Source 1, paragraph 1, when is a society economically stratified?
Answer: D
"If among them there are both wealthy and poor, the society is economically stratified, regardless of whether its organization is communistic or capitalistic." B contradicts that phrase. A contradicts his point that a constitution's labels do not decide the question. C is not his test.
Question 4 of 20 · Multiple Choice
What does Sorokin mean when he says that "Labels, signboards and 'speech reactions'" cannot obliterate economic inequality (Source 1, paragraph 1)?
Answer: A
The sentence follows his point that a society is stratified whether or not "in its constitution it is styled 'the society of equal individuals'": names and declarations do not change "the differences of incomes." B takes "signboards" literally. C reverses his point about written documents. D is advice he does not give.
Question 5 of 20 · Multiple Choice
Why, according to Source 1, paragraph 2, does Sorokin say each form of stratification "has to be studied separately"?
Answer: C
The intercorrelation "is far from being perfect; the strata of each form do not coincide completely with one another," and "This fact does not permit us to analyze in a summary way all three." A overstates the point: he says there is "always a certain degree of overlapping." B and D are not in the passage.
Question 6 of 20 · Multiple Choice
According to Source 2, paragraph 7, what happened to household income at the 90th and 10th percentiles between 2024 and 2025?
Answer: B
"Household income at the 90th percentile increased 1.7% but did not significantly change at the 10th percentile." A applies the 90th-percentile change to both. C reverses the two percentiles. D is not in the passage. The 90th percentile is the income above which the top tenth of households fall; the 10th, the income below which the bottom tenth fall.
Question 7 of 20 · Multiple Choice
Invented example: suppose the median man working full-time, year-round earned $70,000. At the 2025 ratio in Source 2, paragraph 10, what would the median comparable woman earn?
Answer: C
0.839 x $70,000 = $58,730. A is the gap ($70,000 - $58,730), not the woman's earnings. B uses the 2024 ratio of 80.6 percent (0.806 x $70,000 = $56,420). D adds the gap to $70,000 instead of subtracting it.
Question 8 of 20 · Multiple Choice
According to Source 2, paragraph 3, why does a decline in survey response rates matter?
Answer: D
"As response rates decline, the risk of bias increases." The paragraph adds that the Bureau adjusts survey weights to reduce that bias. B confuses the survey's responses with the population it represents. A and C are not in the passage.
Question 9 of 20 · Multiple Choice
In Table A, about how many times the lowest fifth's share of income did the highest fifth receive in 2025?
Answer: A
52.4 / 3.0 is about 17.5, so about 17 times. B divides the highest fifth by the top 5 percent (52.4 / 23.5). C uses the 1967 row (43.6 / 4.0 is about 10.9). D reads the difference, 52.4 - 3.0 = 49.4 percentage points, as a ratio.
Question 10 of 20 · Multiple Choice
In Table A, how much did the top 5 percent's share of income change from 1967 to 2025?
Answer: B
23.5 - 17.2 = 6.3 percentage points. A is the change for the whole highest fifth (52.4 - 43.6). C is the percent change, 6.3 / 17.2 (about 36.6 percent), written as if it were percentage points. D adds the two shares instead of subtracting.
Question 11 of 20 · Multiple Choice
In Table D, by how much did the poverty rate of people 65 and older fall between 1959 and 2025?
Answer: D
35.2 - 9.8 = 25.4 percentage points. A is the fall for ages 18 to 64 (17.0 - 9.2). B is the fall for children (27.3 - 13.4). C adds the two rates.
Question 12 of 20 · Multiple Choice
In Table B, about how many times the median household income of high school graduates was the median for householders with a bachelor's degree?
Answer: B
$127,100 / $60,790 is about 2.09, so about 2.1 times. A compares some college ($76,160) with high school graduates. C uses the professional-degree median ($190,400 / $60,790). D divides the bachelor's median by the less-than-9th-grade median ($127,100 / $36,360).
Question 13 of 20 · Multiple Choice
Which statement describes a pattern of social inequality rather than a single case?
Answer: D
A pattern is a regular difference between groups: Table D shows children (13.4 percent) with a higher poverty rate than adults ages 18 to 64 (9.2 percent). A and C describe one household. B is a single business decision, not a difference between groups of people.
Question 14 of 20 · Multiple Choice
Invented example: in a company, the managers earn the highest pay, decide the work schedules and hold the most respected job titles. Which idea from Source 1 does this example show?
Answer: C
The same people rank highest in pay (economic), authority (political) and job prestige (occupational), which is Sorokin's point that the forms are "closely intercorrelated" as a general rule (paragraph 2). B is wrong because pay is unequal too. A and D contradict the example.
Question 15 of 20 · Short Answer
Sorokin names three principal forms of stratification (Source 1, paragraph 2). Which of them do Tables A-D on this page measure, and which do they not measure? Explain.
Model answer: Tables A, C and D measure economic stratification directly: shares of income, median incomes and poverty rates. Table B measures education, which can serve only as a rough stand-in for occupation, so it touches occupational stratification indirectly at best; none of the tables reports occupations or their prestige. None measures political stratification, which Sorokin describes in paragraph 1 by "the rulers and the ruled" and by authority and prestige. So the page shows mainly economic stratification. Rubric: each of the three forms addressed; the economic tables identified; the gap in political data noted with a quotation.
Question 16 of 20 · Short Answer
Write two accurate pattern sentences from Table C. Then explain why putting Table C next to Table B would not, by itself, show whether differences in education explain the differences in Table C.
Model answer: In 2025 the median household income was $126,300 for Asian-alone householders and $96,710 for White-alone, non-Hispanic householders, compared with $87,460 for all households (Table C). The median was $73,260 for Hispanic householders and $59,980 for Black-alone householders (Table C). Tables B and C are separate tabulations: Table B groups all householders by education and Table C groups them by race and Hispanic origin, so neither shows how education is distributed within each group in Table C, or what the incomes are for people with the same education in different groups. Answering the question would need a table that crosses the two, and it would still leave other differences, such as age, region and household size, uncontrolled. Rubric: two sentences with correct figures and the source; group names as in the table; the missing cross-tabulation explained; no claim about causes.
Question 17 of 20 · Short Answer
Use Table D and Diagram 2 to describe how the pattern of poverty by age changed between 1959 and 2025.
Model answer: In 1959 people 65 and older had the highest poverty rate of the three age groups (35.2 percent), followed by children (27.3 percent) and adults ages 18 to 64 (17.0 percent). By 2025 every group's rate was lower, and the order had changed: children had the highest rate (13.4 percent), while the rates for people 65 and older (9.8 percent) and adults 18 to 64 (9.2 percent) were close together. The pattern of which age group is poorest reversed for older people. Rubric: both years described with correct figures; the change in rank identified; no cause claimed.
Question 18 of 20 · Short Answer
Use Table A to compare the combined share of income of the lowest two fifths with the share of the top 5 percent in 2025. Then explain what the comparison shows.
Model answer: The lowest two fifths, 40 percent of households, received 3.0 + 8.2 = 11.2 percent of income; the top 5 percent received 23.5 percent. 23.5 / 11.2 is about 2.1, so the top 5 percent of households received about twice as much income as the bottom 40 percent combined, a group eight times as large. That is economic stratification in Sorokin's sense: an "unequal distribution" of a valued resource between layers. Rubric: correct sums and ratio; the difference in group sizes noted; the pattern stated without a cause.
Question 19 of 20 · Short Answer
The female-to-male earnings ratio rose from 80.6 percent in 2024 to 83.9 percent in 2025 (Source 2, paragraph 10). Compute the change, and explain two things the ratio by itself does not tell you.
Model answer: 83.9 - 80.6 = 3.3 percentage points. The ratio compares medians for people "both working full-time, year-round" (paragraph 9), so it leaves out part-time and part-year workers. It also does not say why the gap exists: it does not compare women and men in the same jobs, with the same hours beyond full time or the same experience, so researchers use other data to study the causes and do not all agree on them. Rubric: correct change in percentage points; two accurate limits, at least one about who is included and one about causes.
Question 20 of 20 · Short Answer
Invented data: in four invented neighborhoods, the percent of adults with a bachelor's degree is 18, 27, 41 and 55, and the median household income is $48,000, $61,000, $59,000 and $96,000, in the same order. Identify the pattern, the exception, and what Sorokin would say about both.
Model answer: As a rule, neighborhoods with more college graduates have higher median incomes: the neighborhood at 18 percent has the lowest median ($48,000) and the one at 55 percent the highest ($96,000). The exception is the third neighborhood: 41 percent have degrees, but its median ($59,000) is below the second neighborhood's ($61,000). Sorokin would describe this as a "general rule" with "many exceptions": the match between the two rankings "is far from being perfect" (Source 1, paragraph 2). Rubric: the general pattern stated with numbers; the exception identified correctly; a quotation from Sorokin applied.
0 of 20 answered · 0 correct
06
Frequently Asked Questions
10 Questions
What does D2.Soc.15.9-12 mean?
D2.Soc.15.9-12 asks high school students to identify common patterns of social inequality: regular differences between groups in things a society values, such as income, poverty, education and earnings. It opens the C3 sociology companion's cluster on stratification and inequality (Appendix C).
What is the difference between social inequality and social stratification?
Inequality is any unequal distribution of valued things; stratification is inequality that is ranked and lasting, so that a society has upper and lower layers. Sorokin's 1927 definition, used on this page, calls stratification "the differentiation of a given population into hierarchically superposed classes."
What are common patterns of social inequality in the United States?
Official Census data show regular differences by income group (the highest fifth of households received 52.4 percent of income in 2025), by education, by age, by sex and by race and Hispanic origin. The patterns also change over time: older Americans' poverty rate, for example, fell from 35.2 percent in 1959 to 9.8 percent in 2025.
Does D2.Soc.15.9-12 ask students to explain why inequality exists?
No. This indicator asks students to identify patterns. Explaining their effects and causes, and weighing responses to them, belong to D2.Soc.16.9-12, D2.Soc.17.9-12 and D2.Soc.18.9-12. The page asks students to say what data do not show, so that they do not claim causes too early.
What is the difference between a percentage point and a percent?
A percentage point is the difference between two percents; a percent change compares that difference with the starting value. A share that rises from 40 to 50 percent has risen 10 percentage points, which is a rise of 25 percent of the original share. Mixing the two is a common error in reading inequality data.
Where do the numbers on this page come from?
From the U.S. Census Bureau: its September 15, 2026 release on income and poverty in 2025, and its historical income and poverty tables (H-2, H-5, H-13 and Poverty Table 3). They are estimates from the Current Population Survey's Annual Social and Economic Supplement, a survey of households, so each has a margin of error.
How should a class discuss differences by race and ethnicity?
As group medians from official categories, stated accurately, with the reminder that every group includes households at every income level. The page reports the figures and asks students to name the limits of the data; it does not explain or rank causes.
Is Sorokin's 1927 definition still used?
His terms, such as strata and stratification, still appear in sociology courses. This page uses the definition as a historical source and asks students to test one of his claims, that the forms tend to go together, against 2025 data.
Do students share their own family's income?
No. All data on the page are national statistics or invented examples, and no task asks students about their own income, family or circumstances.
Which course teaches D2.Soc.15.9-12?
It is usually taught in a high school sociology elective, in the unit on stratification and inequality. The data skills also fit economics and statistics lessons on reading shares, medians and percentage-point changes.
07
Related Standards
5 standards
These standards connect to D2.Soc.15.9-12: prerequisites to review first, parallel standards at the same level, and next steps that build on it.
Before this lesson
D2.Soc.14.9-12Prerequisite
Explain how in-group and out-group membership affects life chances and norms
Interpret the effects of inequality on groups and individuals
Lesson coming soon
D2.Soc.17.9-12Extends to
Analyze why the distribution of power and inequalities can result in conflict
Lesson coming soon
Standard text: National Council for the Social Studies (NCSS), The College, Career, and Civic Life (C3) Framework for Social Studies State Standards: Guidance for Enhancing the Rigor of K-12 Civics, Economics, Geography, and History (Silver Spring, MD: NCSS, 2013). NCSS was not involved in the production of this lesson and does not endorse it.
