One key can open a gate. Two keys need a plural noun. Most familiar nouns add -s, but boxes, cities and children follow different patterns. Try each sentence before revealing the answer.

01 / BUILD THE FORM

One object, more than one

A singular count noun names one item. A plural count noun names more than one. Look at both the meaning and the noun’s spelling.

One lantern lights this room.
Two lanterns light the hall.

The noun changes from lantern to lanterns. The verb changes too; here, focus on the noun.

Regular -s and common -es forms

Many familiar count nouns add -s: lantern → lanterns. Box takes -es: box → boxes. Watch also takes -es: watch → watches. These patterns help with this set; do not assume every word ending in -ch follows the same rule.

Look before the final y

After a consonant, change final y to -ies: city → cities. After a vowel, keep y and add -s: key → keys; boy → boys.

The map shows one city here
and three cities farther north.

City ends in consonant + y; key ends in vowel + y.

Learn these three irregular forms

Some nouns change in a different way: child → children, foot → feet (the body part), and mouse → mice (the animal). Do not add another -s to children or mice.

One child is waiting. Four children are waiting.

This is a small practice set, not a rule for every plural. Check a learner dictionary when a form is unfamiliar.

02 / YOUR TURN

Try the first four

Write or say the plural of the named noun before opening its answer. Compare your form with the answer; capitalisation, surrounding spaces and final sentence punctuation do not change the plural. There is no automatic grading.

  1. Write the plural of key. Both ___ are on the table.

    Answer and explanation

    keys — Key ends in a vowel plus y, so keep y and add -s.

  2. Write the plural of box. Three wooden ___ block the path.

    Answer and explanation

    boxes — Box takes -es: boxes.

  3. Write the plural of city. The map shows three walled ___.

    Answer and explanation

    cities — With a consonant before final y, change y to -ies.

  4. Write the plural of boy. Two ___ are carrying the flags.

    Answer and explanation

    boys — The letter before y is a vowel, so keep y and add -s.

WHEN YOU’RE READY

Use the rule in a dungeon

Noun Vaults starts at stage 1 with singular and plural nouns, nouns as subjects and proper nouns. The school mixes these foundations; this link opens the game, not a plurals-only quiz. Choose the school manually.

Continue in Noun Vaults

Choose Try a guest descent → Grammar dungeons → Enter Noun Vaults. Guest progress stays on this device.

KEEP PRACTISING

Four more to try

  1. Write the plural of child. All four ___ have a warm coat.

    Answer and explanation

    children — Child has the irregular plural children; do not add -s to it.

  2. Write the plural of foot. The human statue has two stone ___.

    Answer and explanation

    feet — For this body part, foot changes to feet in the plural.

  3. Write the plural of mouse, meaning the small animal. Three grey ___ are hiding behind a box.

    Answer and explanation

    mice — The animal mouse has the irregular plural mice; the animal context removes other senses.

  4. Write the plural of watch. The clockmaker repaired two pocket ___.

    Answer and explanation

    watches — In watch, the final -ch takes -es: watches.

Plural is not possession

For two items, write keys, not key’s. An apostrophe does not make an ordinary plural. Also avoid citys and childrens: compare the ending or recall the irregular form.

Check the forms

These references explain noun forms. The eight exercise contexts here are original.

Cambridge English Grammar Today: nouns — form ↗
British Council: count nouns ↗