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Plurals: When to Add -s, -es or Change y to i

Learn when to add -s or -es, when to change y to i, and how to spot exceptions like leaves and mice, then fix misspelled plurals such as boxs and babys.

Grades 3–5 · 15 practice questions · Original material
Learning objectiveSpell regular plurals by looking at the end of the word: add -s to most nouns, add -es after s, x, z, ch and sh, change consonant + y to -ies, keep vowel + y with -s, and recognise common exceptions such as leaves, children and mice.

The idea

The last lesson was about homophones, words that sound alike. This lesson is about another spelling job you do every day: writing plurals. A plural means more than one: one pencil, two pencils. Most of the time you just add -s, but the end of the word can change the rule.

Rule 1: most nouns add -s: pencil → pencils, toy → toys. Rule 2: if a word ends in s, x, z, ch or sh, add -es: bus → buses, box → boxes, buzz → buzzes, lunch → lunches, dish → dishes. Say the plural aloud. These -es plurals have an extra beat you can hear: box-es.

Rule 3 is for words that end in y. Look at the letter just before the y. If it is a consonant, change y to i and add -es: baby → babies, city → cities. If it is a vowel (a, e, i, o, u), keep the y and just add -s: key → keys, monkey → monkeys.

A few words are exceptions and must be remembered. Some words that end in f change f to v and add -es: leaf → leaves, wolf → wolves. Some words change completely: child → children, mouse → mice. These are not mistakes in the rules; English just kept older forms for them. When a plural looks strange, check a dictionary.

Word bank

pencils

noun (plural) · PEN-sulz

more than one pencil; most nouns just add -s

Example: Sharpen your pencils before the spelling test.

toys

noun (plural) · TOYZ

more than one toy; vowel + y, so just add -s

Example: We packed the toys into a bin.

keys

noun (plural) · KEEZ

more than one key; vowel + y, so just add -s

Example: Mom keeps her keys on a hook by the door.

monkeys

noun (plural) · MUNG-keez

more than one monkey; vowel + y, so just add -s

Example: The monkeys at the zoo swung from rope to rope.

boxes

noun (plural) · BOK-siz

more than one box; ends in x, so add -es

Example: We flattened the boxes for recycling.

buses

noun (plural) · BUS-iz

more than one bus; ends in s, so add -es

Example: Two school buses stopped at the corner.

buzzes

noun (plural) · BUZ-iz

more than one buzz (a humming sound); ends in z, so add -es

Example: We heard buzzes from the bees in the garden.

lunches

noun (plural) · LUN-chiz

more than one lunch; ends in ch, so add -es

Example: The class ate their lunches outside.

dishes

noun (plural) · DISH-iz

more than one dish; ends in sh, so add -es

Example: I dried the dishes after dinner.

babies

noun (plural) · BAY-beez

more than one baby; consonant + y, so change y to i and add -es

Example: The babies were asleep in their strollers.

cities

noun (plural) · SIT-eez

more than one city; consonant + y, so change y to i and add -es

Example: Toronto and Ottawa are cities in Ontario.

stories

noun (plural) · STOR-eez

more than one story; consonant + y, so change y to i and add -es

Example: Grandpa tells the best bedtime stories.

leaves

noun (plural) · LEEVZ

more than one leaf; an exception where f changes to v and you add -es

Example: We raked the maple leaves into a pile.

wolves

noun (plural) · WULVZ

more than one wolf; an exception where f changes to v and you add -es

Example: Wolves live in packs in northern Ontario.

children

noun (plural) · CHIL-drun

more than one child; an irregular plural with no -s at all

Example: The children lined up at the door.

mice

noun (plural) · MICE

more than one mouse; an irregular plural with no -s at all

Example: Two mice ran behind the shed.

Worked examples

Example 1 · Add -s or -es?

Write the plurals of pencil and box.

  1. Look at the last letter of pencil: l. It is not s, x, z, ch or sh, so just add -s: pencils.
  2. Look at the last letter of box: x. Words ending in s, x, z, ch or sh add -es: boxes.
  3. Say them aloud. Box-es has an extra beat you can hear; pencils does not.

pencils, boxes

Example 2 · Consonant + y

Write the plural of story.

  1. Story ends in y. Look at the letter just before y: r.
  2. R is a consonant, so change y to i and add -es.
  3. stor + ies = stories.

stories

Example 3 · Vowel + y

Write the plural of monkey.

  1. Monkey ends in y. Look at the letter just before y: e.
  2. E is a vowel (a, e, i, o, u), so keep the y and just add -s.
  3. monkey + s = monkeys. Monkies is a common misspelling.

monkeys

Example 4 · Spot an exception

Write the plurals of leaf and child.

  1. The usual rule would give leafs, but leaf is an exception: f changes to v and you add -es, so leaves.
  2. Child does not follow any of the rules. Its plural is children.
  3. When a plural sounds different from the rule, check a dictionary. Exceptions like these must be remembered.

leaves, children

Common mistakes

Adding only -s after s, x, z, ch or sh: "two boxs", "three lunchs".

Why this fails: These endings need -es, which adds a beat you can hear: box-es, lunch-es.

Keeping the y after a consonant: "babys", "citys".

Why this fails: When a consonant comes before y, change y to i and add -es: babies, cities.

Changing y to i after a vowel: "monkies", "toies".

Why this fails: When a vowel comes before y, keep the y and just add -s: monkeys, toys.

Adding -s to an irregular plural: "childs", "mouses", "childrens".

Why this fails: Some words have their own plural: children, mice. Children is already plural, so it never takes another -s.

Foundation

Foundation practice

Use the rule table to choose each plural.

Choose

1. Which is the correct plural of fox?

  1. foxs
  2. foxes
  3. foxies
  4. foxess
Choose

2. Which is the correct plural of berry?

  1. berrys
  2. berryes
  3. berries
  4. berres
Choose

3. Which is the correct plural of day?

  1. days
  2. daies
  3. dayes
Choose

4. Which is the correct plural of wish?

  1. wishs
  2. wishies
  3. wishes
Build

5. Write the plural of bench.

Practice

Practice practice

Look at the last letters, then choose or write the plural.

Choose

6. "The ___ at the farm ate apples from my hand." (pony)

  1. ponys
  2. poneys
  3. ponyes
  4. ponies
Choose

7. "We saw wild ___ near the road on our drive." (turkey)

  1. turkies
  2. turkeys
  3. turkeyes
  4. turkeies
Choose

8. "Please wash the paint ___ in the sink." (brush)

  1. brushes
  2. brushs
  3. brushies
  4. brushses
Choose

9. "There are three ___ in our neighbourhood." (library)

  1. librarys
  2. libraryes
  3. libraries
  4. librares
Choose

10. "The cat chased two ___ across the yard." (mouse)

  1. mouses
  2. mousees
  3. mices
  4. mice
Build

11. Write the plural of puppy.

Think

Think practice

Find mistakes, fix them and explain the rule.

Find the correct one

12. Which sentence spells every plural correctly?

  1. The monkeys found two boxes of bananas.
  2. The babys played with their toys.
  3. We packed our lunchs in boxes.
  4. Many citys have big parks.
Fix it

13. Fix every plural: "The childs put their dishs and their toies away."

Explain

14. Explain why the plural of key is keys but the plural of baby is babies.

Write

15. Write one sentence with three plurals: one that adds -s, one that adds -es and one that changes y to i.

Answer key

  1. 1. foxes
    Fox ends in x, so add -es. You can hear the extra beat: fox-es. Foxs is missing the e, and foxies changes the word.
  2. 2. berries
    Berry ends in consonant + y (r + y), so change y to i and add -es. Berrys keeps the y, and berryes forgets to change it.
  3. 3. days
    Day ends in vowel + y (a + y), so just add -s. Daies and dayes would only happen if the letter before y were a consonant.
  4. 4. wishes
    Wish ends in sh, so add -es: wish-es, with an extra beat you can hear. Wishs is hard to say and missing the e.
  5. 5. benches
    Bench ends in ch, so add -es: bench + es = benches. Say it and you hear the extra beat: bench-es.
  6. 6. ponies
    Pony ends in consonant + y (n + y), so change y to i and add -es. Ponys keeps the y; poneys looks like the vowel + y pattern, but the letter before y in pony is n, a consonant.
  7. 7. turkeys
    Turkey ends in vowel + y (e + y), so just add -s. Turkies changes y to i, which only happens after a consonant.
  8. 8. brushes
    Brush ends in sh, so add -es: brush-es. Brushs is missing the e you need to make the extra beat.
  9. 9. libraries
    Library ends in consonant + y (r + y), so change y to i and add -es. Librarys keeps the y, which is the most common mistake with this pattern.
  10. 10. mice
    Mouse is an exception. Its plural is mice, with no -s at all. Mouses and mousees follow the usual rules, but this word does not.
  11. 11. puppies
    Puppy ends in consonant + y (p + y), so change y to i and add -es: pupp + ies = puppies.
  12. 12. The monkeys found two boxes of bananas.
    Monkey ends in vowel + y, so add -s (monkeys); box ends in x, so add -es (boxes). The other sentences have a mistake: babys should be babies, lunchs should be lunches, and citys should be cities.
  13. 13. The children put their dishes and their toys away.
    Child is an exception: children. Dish ends in sh, so add -es: dishes. Toy ends in vowel + y, so just add -s: toys.
  14. 14. Look at the letter before y. In key, e is a vowel, so just add -s. In baby, b is a consonant, so change y to i and add -es.
    The letter just before y decides the rule: vowel + y adds -s; consonant + y changes y to i and adds -es.
  15. 15. Example: The puppies chewed my socks and two boxes.
    Check each plural against the rule table: puppies (consonant + y), socks (just add -s), boxes (ends in x, add -es).

Related practice

Homophones: there, their and they'reSuffixes -ful, -less and -nessEnglish hub