Regular Plural Formation

• General Rule: For most nouns, add -s to form the plural.
• Examples:
  • cat → cats
  • book → books
  • dog → dogs

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Nouns Ending in -s, -ss, -sh, -ch, -x, or -z

• Rule: Add -es to form the plural.
• Examples:
  • bus → buses
  • class → classes
  • bush → bushes
  • watch → watches
  • box → boxes
  • quiz → quizzes

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Nouns Ending in -f or -fe

• Rule: Change the -f or -fe to -ves.
• Examples:
  • leaf → leaves
  • wolf → wolves
  • knife → knives
  • Exceptions: Some nouns just add -s.
    • roof → roofs
    • chef → chefs
    • belief → beliefs

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Nouns Ending in – o

• Rule: Add -es.
• Examples:
  • potato → potatoes
  • hero → heroes
  • Exceptions: Some nouns just add -s.
    • piano → pianos
    • photo → photos
    • halo → halos

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Nouns Ending in -y

• Rule: If a noun ends in a consonant + -y, change the -y to -ies.
• Examples:
  • baby → babies
  • city → cities
  • party → parties
  • Exceptions: If a noun ends in a vowel + -y, just add -s.
    • boy → boys
    • day → days
    • key → keys

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Nouns Ending in -us, -is, -on, and -um

• Rule for -us: Change to -i.
• Examples:
  • cactus → cacti
  • focus → foci
• Rule for -is: Change to -es.
• Examples:
  • analysis → analyses
  • thesis → theses
• Rule for -on: Change to -a.
• Examples:
  • phenomenon → phenomena
  • criterion → criteria
• Rule for -um: Change to -a.
• Examples:
  • datum → data
  • bacterium → bacteria

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Irregular Plurals

• Some nouns have irregular plural forms that do not follow typical rules.
• Examples:
  • child → children
  • foot → feet
  • tooth → teeth
  • mouse → mice
  • person → people

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Unchanging Nouns

• Some nouns have the same form in both singular and plural.
• Examples:
  • sheep → sheep
  • deer → deer
  • species → species
  • fish → fish (context-dependent)

Let’s practice!✒️