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Plurals and Possessives

Scientist's, scientists or scientists'? Irregular plurals, its/it's, whose/who's, their/they're/there and joint possession — rules, method, worked examples and a 12-question practice quiz.

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What this question type tests

Plural and possessive questions are part of Standard English Conventions (about 26% of the scored Reading and Writing questions, usually 11–15 of them), in the skill Form, Structure, and Sense. The official skill list names plural and possessive nouns, and the pronoun pairs its/it's, their/they're/there and your/you're. This page also covers whose/who's, which follows exactly the same logic. Grammar questions usually appear after the reading questions in each module.

The stem is the usual conventions stem: "Which choice completes the text so that it conforms to the conventions of Standard English?" The four choices are the same word written in different ways — for example scientist's / scientists / scientists' / scientist — or a pair of words in which both may need an apostrophe, such as colony's members / colonies' members' / colonies members. You do not need to understand the science in the passage; you need to answer two small questions: Is it possessive? Is it singular or plural?

The three forms you must tell apart

Meaning	Form	Example	Test with "of"
more than one (no ownership)	noun + s — NO apostrophe	The scientists met in Cairo.	—
one owner	noun + 's	The scientist's notebook was lost.	the notebook of the scientist
more than one owner (regular plural)	noun + s'	The scientists' notebooks were lost.	the notebooks of the scientists
more than one owner (irregular plural)	plural + 's	The children's library opened.	the library of the children

The "of" test: turn the phrase around using "of". If you can say "the notebook of the scientist", you need a possessive. Then look at the noun after "of": if it is one (the scientist), write 's; if it is a plural ending in s (the scientists), write s'. If no "of" phrase makes sense, there is no ownership, so there is no apostrophe.

✗ The scientist's met in Cairo. (Nothing is owned — just more than one scientist.)
✓ The scientists met in Cairo.
✗ Both teams coaches praised the players. (The coaches of the teams → possessive needed.)
✓ Both teams' coaches praised the players.
✗ Each students' project was displayed. ("Each" = one student.)
✓ Each student's project was displayed.

How to know if the noun is singular or plural

The passage always gives you a clue. Never guess — find the clue.

Clue in the text	Points to	Example
a, an, one, each, every, this, that	singular	each volunteer's interview
numbers above one, many, several, both, these, those, all	plural	several villages' wells
a singular verb later (is, was, has)	singular	the colony's health was…
earlier sentence: "a team of ecologists", "two orchestras"	follow the earlier sentence	the orchestras' conductors
"their" or "its" referring back	plural / singular	the farmers… their crops

Irregular plurals

Some nouns make their plural without -s. For these, the possessive is simply plural + 's. Never write "childrens'" or "peoples'" (unless you mean several nations — "peoples").

Singular	Plural	Plural possessive
child	children	children's
person	people	people's
man / woman	men / women	men's / women's
mouse	mice	mice's
tooth	teeth	teeth's
foot	feet	feet's
goose	geese	geese's

Academic nouns from Latin and Greek also appear in SAT science passages: phenomenon → phenomena, criterion → criteria, datum → data, bacterium → bacteria, nucleus → nuclei, species → species (same form). Their possessives follow the same rule: the bacteria's genes, a phenomenon's cause.

Pronouns: possessives have NO apostrophe

This is the rule that confuses most students. Possessive pronouns never use an apostrophe. When a pronoun has an apostrophe, it is a contraction — two words joined together.

Possessive (shows ownership)	Contraction (two words)	Quick test
its — The octopus changed its colour.	it's = it is / it has — It's hiding.	Say "it is". If it works, write it's.
their — The farmers sold their crops.	they're = they are — They're ready.	Say "they are".
(there = place / there is)		"There are five species."
whose — the writer whose book won	who's = who is / who has — the writer who's visiting	Say "who is".
your — your answer	you're = you are	Say "you are".

"its'" does not exist in English. If you see it in a choice, cross it out immediately. The same is true of "their's" and "your's".

✗ The museum reopened it's east wing. → ✓ The museum reopened its east wing.
✗ Its likely that the bridge will close. → ✓ It's likely that the bridge will close. (it is likely)
✗ The bees return to they're hive. → ✓ The bees return to their hive.
✗ The poet, who's collection won the prize, … → ✓ The poet, whose collection won the prize, …

Compound nouns, names and joint possession

Compound nouns: add 's to the last word. my sister-in-law's car; the editor-in-chief's decision. The plural changes the main word: two sisters-in-law.
Joint possession (they share one thing): put 's only on the last name. Omar and Dina's design (one design they made together).
Separate possession (each has his or her own): put 's on every name. Omar's and Dina's designs (two different designs). The owned noun is usually plural.
Organisations and places: they are singular. the company's profits; Egypt's population; the university's students.
Singular nouns ending in -s: add 's — the bus's route, James's essay. SAT questions rarely depend on this case.

سؤالين بس قبل ما تختار

١) فيه ملكية؟ جرّب of: لو ينفع تقول the notebook of the scientist يبقى محتاج apostrophe. لو مفيش ملكية، مفيش apostrophe خالص.
٢) مفرد ولا جمع؟ دوّر على clue في الجملة: each / a = مفرد → 's — several / both / رقم = جمع → s'.
الضماير ماليهاش apostrophe في الملكية: its, their, whose, your. لو فيه apostrophe يبقى اختصار: it's = it is.

The method for two-word choices

Hard questions put two nouns in each choice, for example "the farmer's crops" vs "the farmers' crops'". Treat each word separately.

Word 1: Does it own word 2? (Usually yes — that is why the two words sit together.) Is it singular or plural? Choose 's or s'.
Word 2: Does it own the next word? Usually no — the next word is a verb or a preposition, so word 2 has no apostrophe. Decide only whether it is singular or plural.
Check the verb: "the crops were damaged" needs a plural; "the crop was" needs a singular.
Eliminate any choice with an apostrophe on a word that owns nothing.

Quick drill: fix the sentence

Decide whether each sentence is correct. If not, correct it, then open the answer.

The researcher's collected samples from three lakes.
Show answer
Wrong. Nothing is owned ("collected" is a verb), so: The researchers collected samples from three lakes.
Both cities' mayors attended the conference.
Show answer
Correct. Two cities own the mayors → plural possessive cities'.
The company announced it's new policy on Monday.
Show answer
Wrong. Possessive pronoun: its new policy.
The womens' team won the final.
Show answer
Wrong. Women is an irregular plural: women's team.
Each players' locker has a name tag.
Show answer
Wrong. "Each" = one player: player's locker.
Its been ten years since the bridge opened.
Show answer
Wrong. It has been → It's been ten years.
Ahmed's and Laila's house is near the river.
Show answer
Wrong if they share one house: Ahmed and Laila's house.
The scientist, who's research focuses on coral, spoke first.
Show answer
Wrong. Ownership → whose research.

Worked examples

Worked example 1: plural possessive

In 2024, a team of ecologists surveyed honeybee colonies on farms near Fayoum. They discovered that the ______ health depended largely on the variety of flowers growing within two kilometers of each hive.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) colonies
B) colony's
C) colonies'
D) colonys'

Answer: C) colonies'

Of test: "the health of the colonies" → possessive. The team surveyed many colonies (plural), so the plural possessive "colonies'" is correct (C).
A is wrong: no apostrophe, so it is a simple plural and cannot own "health".
B is wrong: singular possessive, but the ecologists surveyed more than one colony.
D is wrong: "colonys" is not a word; the plural of colony is colonies.

Worked example 2: a two-word choice

Archaeologist Rania Saleh studies villages where the builders of ancient Egyptian monuments lived. In one village, she found that each ______ a small clay oven, suggesting that families baked their own bread.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) households' kitchen contained
B) household's kitchen contained
C) households kitchen contained
D) household's kitchens' contained

Answer: B) household's kitchen contained

"Each" means one household, so word 1 is a singular possessive: household's. Word 2, "kitchen", owns nothing (the next word is a verb), so it has no apostrophe. Choice B.
A is wrong: "households'" is plural, but "each" is singular.
C is wrong: "households" has no apostrophe, so it cannot own the kitchen.
D is wrong: "kitchens'" has an apostrophe but owns nothing.

Worked example 3: its / it's

The giant Pacific octopus is a master of disguise. It can change both the color and the texture of ______ skin in less than a second, a skill that helps it hide from predators among rocks and seaweed.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) it's
B) its'
C) their
D) its

Answer: D) its

The skin belongs to the octopus (one animal), so we need the singular possessive pronoun "its" — no apostrophe. Choice D.
A is wrong: "it's" = it is. "the texture of it is skin" makes no sense.
B is wrong: "its'" does not exist in English.
C is wrong: "their" is plural, but "the giant Pacific octopus" is singular (and the text uses "it").

Worked example 4: joint possession

The city library's new reading room for young visitors opened in March. It was designed by two architects, Omar Hegazy and Dina Farag, who worked together on every stage of the project. ______ design includes low shelves and floor cushions so that children can reach every book.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) Hegazy and Farag's
B) Hegazy's and Farag's
C) Hegazy and Farags'
D) Hegazy's and Farag

Answer: A) Hegazy and Farag's

The two architects worked together on one design, so this is joint possession: 's on the last name only. Choice A.
B is wrong: 's on both names means separate possession — two different designs — but the text describes one shared design.
C is wrong: "Farags'" treats one person's name as a plural.
D is wrong: Farag has no possessive, so the phrase does not show that the design is theirs.

Classic traps

The decoration apostrophe: an apostrophe on a simple plural ("the scientist's met"). If nothing is owned, there is no apostrophe.
The number trap: "each" or "a" before the noun means singular even when the passage is about many things.
The double apostrophe: an apostrophe on the second word too ("farmers' crops'"). The second word usually owns nothing.
its' and childrens': forms that do not exist. Cross them out at once.
its vs it's / whose vs who's: possessive pronouns never take an apostrophe; read it's as "it is" to check.
Joint vs separate: "each developed a filter" → Fahmy's and Adel's filters; "worked together" → Fahmy and Adel's filter.

Fast strategy for test day

Ask the two questions in order: Does it own something? One or many?
Use the "of" test when you are unsure about ownership.
For pronouns, say the long form aloud in your head: it is, they are, who is, you are.
For two-word choices, decide word 1 and word 2 separately and check the verb.
These are among the fastest questions on the test — 20–40 seconds each.

Practice

Remember

No ownership = no apostrophe (scientists). One owner = 's (scientist's). Many owners = s' (scientists').
Irregular plurals take 's: children's, people's, women's.
Possessive pronouns have no apostrophe: its, their, whose, your. It's = it is; who's = who is.
Find the singular/plural clue: each, a, several, both, numbers, and the verb.
Shared ownership: Omar and Dina's. Separate ownership: Omar's and Dina's.

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