SAT Grammar: Plurals and Possessives
Master apostrophe rules and plural formations for the SAT Reading & Writing section
Plurals and possessives are among the most frequently tested conventions on the SAT. Understanding when to use apostrophes—and when not to—is essential for achieving a top score in the Reading and Writing section.
What are Plurals and Possessives?
Key Definitions:
Plurals: Nouns and pronouns that refer to more than one thing (usually formed by adding -s or -es, no apostrophe)
Possessives: Nouns and pronouns that show ownership or belonging (require apostrophes for nouns, but never for pronouns)
❌ Incorrect:
One cannot overstate the importance of bee's to the pollination of Michigans blueberry crop.
✓ Correct:
One cannot overstate the importance of bees to the pollination of Michigan's blueberry crop.
Explanation: "Bees" is plural (no apostrophe); "Michigan's" is possessive (apostrophe before s).
🎯 The Golden Rule:
Plural nouns do NOT use apostrophes—they simply add -s or -es. Only possessive nouns require apostrophes. This is the SAT's #1 trap!
How to Form Plurals
Plural formation follows predictable patterns. Understanding these rules helps you avoid unnecessary apostrophes.
Regular Plural Formation
| Rule | Example |
|---|---|
| Most nouns: add -s | cat → cats, dog → dogs, book → books |
| Nouns ending in -s, -ss, -sh, -ch, -x, -z: add -es | class → classes, brush → brushes, box → boxes |
| Nouns ending in consonant + y: change y to i, add -es | baby → babies, city → cities, story → stories |
| Nouns ending in vowel + y: add -s | key → keys, boy → boys, day → days |
| Most nouns ending in -o: add -s | piano → pianos, photo → photos |
| Some nouns ending in -f or -fe: change to -ves | leaf → leaves, knife → knives, wolf → wolves |
⚠️ Critical Rule:
Regular plural nouns NEVER use apostrophes. If you see "book's" when the sentence means "multiple books," it's wrong!
Irregular Plural Formation
Some nouns don't follow standard plural rules. These irregular plurals are important for possessive formation.
| Type | Examples |
|---|---|
| Vowel change | man → men, woman → women, foot → feet, tooth → teeth |
| Add -en/-ren | child → children, ox → oxen |
| Same form (singular = plural) | sheep, deer, fish, species, series |
| Latin/Greek origin | criterion → criteria, analysis → analyses, nucleus → nuclei |
💡 SAT Tip:
Irregular plurals that don't end in -s (children, men, women) form possessives by adding 's (children's, men's, women's).
How to Form Possessives
Possessives show ownership or belonging. The apostrophe rules differ based on whether the noun is singular or plural.
Singular Possessive Nouns
Rule for Singular Possessives:
Add apostrophe + s ('s) to ANY singular noun, even if it already ends in "s"
Standard Examples:
• The dog's collar (one dog)
• The company's products
• Maria's book
Ends in "s" Already:
• James's car
• The boss's office
• The rhinoceros's horn
Example in Context:
The company's most popular products include shampoo and moisturizer.
One company owns the products → singular possessive with 's
Plural Possessive Nouns
Rules for Plural Possessives:
1. If plural ends in -s: Add apostrophe AFTER the s (s')
2. If plural doesn't end in -s: Add apostrophe + s ('s)
Plural Ends in -s:
• The dogs' collars (multiple dogs)
• The students' projects
• The heroes' costumes
Plural Doesn't End in -s:
• The children's playground
• The men's swim team
• The women's rights movement
Examples in Context:
✓ On many superhero teams, the heroes' costumes are each a different color.
Multiple heroes own costumes → plural possessive, apostrophe after s
✓ The men's swim team won the championship.
"Men" is plural but doesn't end in s → add 's
Possessive Pronouns
🚨 CRITICAL RULE:
Possessive pronouns NEVER use apostrophes!
| Possessive Pronoun | Common Confusion | Meaning |
|---|---|---|
| its (belongs to it) | it's (it is) | Possessive vs. Contraction |
| their (belongs to them) | they're (they are), there (location) | Possessive vs. Contraction vs. Location |
| your (belongs to you) | you're (you are) | Possessive vs. Contraction |
| whose (belongs to whom) | who's (who is) | Possessive vs. Contraction |
Examples:
✓ The dog wagged its tail. (possessive—no apostrophe)
✓ It's raining outside. (contraction for "it is")
✓ The students forgot their homework. (possessive)
✓ They're going to the movies. (contraction for "they are")
Common SAT Traps & Pitfalls
Trap #1: Unnecessary Apostrophes in Plurals
The SAT's #1 trap is adding apostrophes to simple plural nouns. Remember: plurals do NOT need apostrophes unless they're also possessive.
🎯 Test Strategy:
If you see an apostrophe, ask: "Does something belong to this noun?" If no, remove the apostrophe!
Common Errors:
❌ The restaurant owner's target high-class diner's.
✓ The restaurant owners target high-class diners.
Both "owners" and "diners" are simply plural—nothing belongs to them.
Trap #2: Multiple Nouns Requiring Different Forms
The SAT often tests two nouns in one sentence—one needs to be possessive, the other plural. You must evaluate each noun separately.
🎯 Test Strategy:
Use the "of" test for each noun: Does it make sense to say "X of the [noun]"? If yes, it's possessive.
Example:
The anthology included ______ from several ______ most celebrated works.
First noun ("poems"): More than one poem → plural (no apostrophe)
Second noun ("novelist"): "Works of the novelist" → possessive (needs apostrophe)
✓ Correct: The anthology included poems from several novelists' most celebrated works.
Trap #3: Its vs. It's (and Their vs. They're)
This is the SAT's most common possessive pronoun trap. Remember the ironclad rule: possessive pronouns never use apostrophes.
🎯 Test Strategy:
If you can replace it with "it is" or "they are," use the apostrophe version. If not, it's possessive (no apostrophe).
Its / It's:
❌ The company lost it's market share.
✓ The company lost its market share.
"It is market share" doesn't work → possessive
Their / They're / There:
❌ The students lost they're books.
✓ The students lost their books.
"They are books" doesn't work → possessive
Trap #4: Singular Nouns Already Ending in "s"
Many students incorrectly assume that singular nouns ending in "s" should only get an apostrophe. Wrong! All singular nouns get 's, even if they end in "s."
Rule:
Singular noun (even ending in s) → Add 's
Examples:
✓ James's car is in the parking lot.
✓ The boss's decision was final.
✓ Chris's presentation was excellent.
All singular → all get 's
Trap #5: Determining Singular vs. Plural from Context
The SAT tests whether you can determine from context clues if a possessive should be singular or plural.
🎯 Key Words to Watch:
Singular indicators: each, every, a, an, one
Plural indicators: all, both, several, many, multiple
Examples:
✓ Every contestant's goal was to win. (each one individually → singular)
✓ All contestants' buzzers were broken. (multiple contestants → plural)
Fully Worked SAT-Style Examples
Example 1: Plural vs. Singular Possessive
The anthology of contemporary American poetry included ______ from several ______ most celebrated works.
A) poems . . . novelist's
B) poem's . . . novelist's
C) poems . . . novelists'
D) poem's . . . novelists'
Step-by-Step Solution:
Step 1: Evaluate the first blank ("poems").
Question: Are we discussing more than one poem?
Answer: Yes—the anthology "included" multiple poems.
Question: Does something belong to the poems?
Answer: No—nothing comes after "poems" that belongs to them.
Conclusion: "poems" must be PLURAL (no apostrophe).
Step 2: Eliminate based on first word.
Choices B and D use "poem's" (singular possessive) ❌
Only A and C remain.
Step 3: Evaluate the second blank ("novelist").
Question: Is this one novelist or several novelists?
Answer: "Several" indicates more than one → plural
Question: Do the works belong to the novelists?
Answer: Yes—"works of the novelists" makes sense → possessive
Conclusion: "novelists'" (plural possessive—apostrophe after s).
Step 4: Apply the rule.
• A) novelist's = singular possessive ❌
• C) novelists' = plural possessive ✓
Answer: C – "poems" is plural; "novelists'" is plural possessive.
Example 2: Its vs. It's
Scientists have long known that soot particles facilitate melting by darkening snow and ice, limiting ______ ability to reflect the Sun's rays.
A) it's
B) its'
C) its
D) their
Step-by-Step Solution:
Step 1: Identify what the pronoun refers to.
What has the ability to reflect rays? "Snow and ice"
The pronoun must refer to this antecedent.
Step 2: Test the contraction.
Can we replace the blank with "it is"?
"...limiting it is ability to reflect..." ❌ This doesn't work.
Therefore, we need the possessive form, not the contraction.
Step 3: Check number agreement.
"Snow and ice" is technically two things joined by "and," but when used together as a compound subject functioning as one entity, it's treated as singular in this context.
More importantly, the verb "limiting" treats it as singular.
Step 4: Apply possessive pronoun rules.
• A) it's = contraction ❌
• B) its' = not a real form ❌
• C) its = singular possessive pronoun (no apostrophe) ✓
• D) their = plural possessive (agreement issue) ❌
Answer: C – "its" is the possessive pronoun form (no apostrophe for pronouns).
Example 3: Unnecessary Apostrophes
The couple ordered several ______ to satiate their appetite for the ______ food.
A) dishes . . . chef's
B) dishes' . . . chef's
C) dish's . . . chefs
D) dishes' . . . chefs
Step-by-Step Solution:
Step 1: Evaluate the first blank ("dishes").
Question: How many dishes? "Several" → plural
Question: Does something belong to the dishes?
Answer: No. The sentence just says they ordered multiple dishes.
Conclusion: "dishes" is PLURAL only (no apostrophe).
Step 2: Recognize the trap.
The SAT wants you to add an apostrophe to "dishes" because it comes before "to satiate."
But nothing belongs to the dishes—they're just plural.
Step 3: Eliminate wrong answers.
B and D use "dishes'" ❌
C uses "dish's" (singular possessive) ❌
Only A remains with "dishes" (plural, no apostrophe) ✓
Step 4: Verify the second blank ("chef's").
Use the "of" test: "food of the chef" = chef's food ✓
One chef owns the food → singular possessive with 's
Answer: A – "dishes" is plural (no apostrophe); "chef's" is singular possessive.
Example 4: Their vs. They're vs. There
The researchers presented ______ findings at the conference, and ______ confident that the data will revolutionize the field.
A) their . . . there
B) they're . . . their
C) their . . . they're
D) there . . . they're
Step-by-Step Solution:
Step 1: Evaluate the first blank.
Question: Whose findings? The researchers' findings.
This shows possession: "findings of the researchers"
Conclusion: Need possessive "their" (not they're or there).
Step 2: Eliminate based on first word.
B uses "they're" (contraction) ❌
D uses "there" (location/existential) ❌
Only A and C remain with "their" ✓
Step 3: Evaluate the second blank.
Can we replace it with "they are"?
"...and they are confident that..." ✓ This works!
Conclusion: Need the contraction "they're"
Step 4: Check both positions.
• A) their . . . there ❌ ("there confident" is wrong)
• C) their . . . they're ✓ (possessive + contraction)
Answer: C – "their" shows possession; "they're" = "they are"
Example 5: Irregular Plural Possessive
The ______ ice cream stand was extremely popular, causing the ______ long wait times to exceed an hour on weekends.
A) childrens' . . . customers
B) children's . . . customers'
C) childrens . . . customer's
D) children's . . . customers
Step-by-Step Solution:
Step 1: Evaluate the first blank ("children").
"Children" is already a plural form (irregular—doesn't end in s).
Question: Does the ice cream stand belong to children?
Answer: Yes—"ice cream stand of the children" = possessive
Rule: Irregular plurals not ending in s → add 's
Conclusion: "children's" (not "childrens'" or "childrens").
Step 2: Eliminate wrong answers.
• A) "childrens'" is incorrect form ❌
• C) "childrens" (no apostrophe) ❌
Only B and D have "children's" ✓
Step 3: Evaluate the second blank ("customers").
Question: Does something belong to the customers?
Let's check: "wait times of the customers"?
Answer: No! The wait times exist for everyone—they don't belong to specific customers.
Conclusion: "customers" is just plural (no apostrophe).
Step 4: Finalize the answer.
• B) customers' = plural possessive ❌
• D) customers = plural (no apostrophe) ✓
Answer: D – "children's" (irregular plural possessive); "customers" (simple plural)
Example 6: Singular Noun Ending in S
The ______ decision to implement the new policy was met with widespread support from ______ members.
A) boss' . . . staff
B) boss's . . . staff
C) bosses' . . . staffs
D) bosses . . . staffs'
Step-by-Step Solution:
Step 1: Determine singular vs. plural for "boss."
Clue: "The boss" and singular verb "was"
This refers to ONE boss → singular
Question: Does the decision belong to the boss?
Answer: Yes—"decision of the boss"
Rule: Singular possessive (even ending in s) → add 's
Conclusion: "boss's" (NOT "boss'").
Step 2: Eliminate wrong answers.
• A) "boss'" = incorrect form for singular ❌
• C) "bosses'" = plural possessive ❌
• D) "bosses" = plural non-possessive ❌
Only B has "boss's" ✓
Step 3: Verify the second blank ("staff").
Question: How many staff members? Multiple → could be plural
Question: Does something belong to the staff members?
Answer: No—they're just members of the staff.
Conclusion: "staff" is singular collective or "staff members" is descriptive (no possessive).
Step 4: Confirm the answer.
B uses "staff" (correct form without apostrophe) ✓
Answer: B – "boss's" (singular possessive even though it ends in s); "staff" (no apostrophe needed)
Example 7: Context-Dependent Singular vs. Plural
Every ______ goal was to finish the marathon, and all of the ______ training regimens included long-distance runs.
A) runner's . . . runners'
B) runners' . . . runner's
C) runners . . . runners
D) runner's . . . runner's
Step-by-Step Solution:
Step 1: Analyze the first blank with "Every."
Key word: "Every" = each individual runner (singular)
Question: Does the goal belong to the runner?
Answer: Yes—"goal of every runner"
Conclusion: "runner's" (singular possessive).
Step 2: Eliminate based on first word.
• B) "runners'" = plural possessive ❌
• C) "runners" = plural no apostrophe ❌
Only A and D remain with "runner's" ✓
Step 3: Analyze the second blank with "all."
Key word: "All" = multiple runners (plural)
Question: Do the training regimens belong to the runners?
Answer: Yes—"training regimens of all the runners"
Rule: Plural possessive ending in s → apostrophe after s
Conclusion: "runners'" (plural possessive).
Step 4: Check both answers.
• A) runner's . . . runners' ✓ (singular possessive + plural possessive)
• D) runner's . . . runner's ❌ (both singular)
Answer: A – "Every runner's" (singular); "all runners'" (plural possessive)
Top Test-Day Strategies
1. The "Of" Test
To determine if a noun needs an apostrophe, rewrite with "of": "The school's policy" = "the policy of the school." If it works, it's possessive!
2. Check Each Noun
When a question has two nouns, evaluate each separately. One might be possessive while the other is just plural.
3. Contraction Test
For it's/its or they're/their, substitute the full form. If "it is" or "they are" works, use the apostrophe version. If not, it's possessive (no apostrophe).
4. Context Clues
Words like "every" and "each" signal singular; "all," "both," and "several" signal plural. Use these to determine apostrophe placement.
5. Memorize the Rules
Singular → 's | Plural ending in s → s' | Plural not ending in s → 's | Possessive pronouns → NEVER apostrophes
6. Beware Simple Plurals
The SAT's favorite trap: adding unnecessary apostrophes to plain plural nouns. If nothing belongs to it, don't add an apostrophe!
Quick Reference Chart
| Form | Rule | Example |
|---|---|---|
| Regular plural | Add -s or -es (NO apostrophe) | cats, boxes, cities |
| Singular possessive | Add 's (even if ends in s) | cat's, James's, boss's |
| Plural possessive (ends in s) | Add apostrophe after s | cats', students', heroes' |
| Plural possessive (no s) | Add 's | children's, men's, women's |
| Possessive pronoun | NEVER use apostrophe | its, their, whose, your |
| Contraction | Use apostrophe to replace letters | it's (it is), they're (they are) |
Key Takeaways
- Plural nouns never use apostrophes—this is the SAT's #1 trap
- Singular possessive: always add 's, even if the noun already ends in "s"
- Plural possessive ending in s: add apostrophe after the s (s')
- Irregular plural possessive (no s): add 's (children's, men's, women's)
- Possessive pronouns (its, their, whose, your) NEVER use apostrophes
- It's = it is | Its = possessive (no apostrophe)
- They're = they are | Their = possessive | There = location
- Use the "of" test to determine if a noun should be possessive
- Context clues like "every" (singular) vs. "all" (plural) help determine apostrophe placement
- When a sentence has two nouns, evaluate each one independently
Master these plurals and possessives rules, and you'll never miss an apostrophe question again! Remember: when in doubt, use the "of" test.