Irregular Plurals Grammar Quiz
12 multiple-choice questions on irregular plurals: vowel change plurals like 'children' and 'mice', zero plurals, and Latin and Greek forms like 'criteria'. B1–C1 level.
This quiz checks how confidently you can apply Irregular Plurals at B1–C1 level, with questions built around real forms such as men, teeth, children, sheep and leaves rather than abstract rule statements. Each question presents a full example sentence, so you have to judge which form fits the meaning and structure correctly instead of recalling a rule in isolation.
If a question catches you out, the FAQ section below explains the underlying rule in more detail, including common mistakes learners make with this point. Reviewing the explanation immediately after an incorrect answer, then retrying the quiz on a different day, builds more durable grammar knowledge than repeating the same 12 questions back to back.
Irregular Plurals — FAQ
What is a 'vowel change' plural?
A vowel change plural forms its plural by changing an internal vowel rather than adding -s, such as 'man' to 'men', 'woman' to 'women', 'foot' to 'feet', 'tooth' to 'teeth', 'mouse' to 'mice' and 'goose' to 'geese'. These are among the oldest irregular plural patterns in English.
What is a 'zero plural'?
A zero plural noun has the same form in both singular and plural, such as 'sheep', 'deer', 'fish', 'species' and 'aircraft'. For example, 'The farmer kept twenty sheep' uses 'sheep' as a plural without adding any ending.
How do nouns ending in -f or -fe usually form their plural?
Many nouns ending in -f or -fe change this ending to -ves in the plural, such as 'leaf' to 'leaves', 'knife' to 'knives', 'wife' to 'wives', 'life' to 'lives' and 'half' to 'halves'. However, this rule has exceptions, such as 'roof', which simply becomes 'roofs'.
How do Latin words ending in -um form their plural?
Latin-origin nouns ending in -um typically change to -a in the plural, such as 'datum' to 'data', 'medium' to 'media' and 'curriculum' to 'curricula'. In modern English, 'data' is often used as an uncountable mass noun, though technically it is the plural of 'datum'.
How do Latin words ending in -us form their plural?
Latin-origin nouns ending in -us often change to -i in the plural, such as 'cactus' to 'cacti', 'nucleus' to 'nuclei' and 'syllabus' to 'syllabi'. Some of these also have accepted regular plurals in everyday English, such as 'cactuses'.
How do Greek words ending in -is form their plural?
Greek-origin nouns ending in -is typically change to -es in the plural, such as 'analysis' to 'analyses', 'basis' to 'bases', 'crisis' to 'crises' and 'thesis' to 'theses'. Note the pronunciation change from a short 'i' sound to a long 'ee' sound in the plural.
How do Greek words ending in -on form their plural?
Greek-origin nouns ending in -on typically change to -a in the plural, such as 'criterion' to 'criteria' and 'phenomenon' to 'phenomena'. A common learner mistake is treating 'criteria' or 'phenomena' as singular, since they already look plural to English speakers unfamiliar with Greek.
What is the correct plural of 'child'?
The correct plural of 'child' is 'children', formed with the archaic -en ending rather than a regular -s. A common mistake is saying 'childs' or 'childrens', but the correct form takes no additional -s after 'children'.
What is a common mistake with 'criterion' and 'phenomenon'?
A common mistake is adding a regular -s to form 'criterions' or 'phenomenons' instead of using the correct Greek-derived plurals 'criteria' and 'phenomena'. Another related mistake is using 'criteria' or 'phenomena' as if they were singular nouns, such as saying 'this criteria' instead of 'this criterion'.
What is a common mistake with zero-plural nouns like 'sheep' and 'deer'?
A common mistake is adding an unnecessary -s, producing incorrect forms like 'sheeps' or 'deers'. Since these nouns are zero plurals, the same form is used for both singular and plural, and the correct number is understood from context or from a preceding number word.