Why does baby become babies but boy stays boys?

Look at the letter before the y. A consonant before y (baby, city, puppy) means the y changes to -ies. A vowel before y (boy, day, key) means plain -s. It's the one plural rule worth memorizing as a rule rather than by ear, because the sound doesn't give it away.

What are the -ves plurals?

A family of f-words trades f for -ves: leaf/leaves, wolf/wolves, shelf/shelves, knife/knives. Not every f-word does it (roofs, chiefs), so third graders learn the common -ves set as a list and treat the rest as regular.

3rd grade plural noun rules

3rd grade plural noun rules worksheets

Plural spelling follows patterns: add -s for most nouns, -es after x, ch, sh, and s sounds, -ies for consonant + y words, and -ves for many f words. Third graders work across all the families and catch misspellings like foxs and babys.

Free printable PDF worksheet, aligned to Common Core L.3.1.b.

Each print is a different sheet with its own answer key. You don't need to sign up.

The kind of sentences you'll fix

Write the plural of the word in parentheses to complete each sentence.

Rosa found both (key) under the doormat.
Fixed: Rosa found both keys under the doormat.
Many (star) glittered over the campsite.
Wei filled five (glass) with cold lemonade.

Every print pulls a new set of sentences at this level, so a make-up test or a second sibling gets a different mix.

What's on a 3rd grade sheet

3rd grade sheets draw from 80 sentences, 8 to a page. All 60 of 2nd grade's sentences are here too, plus 20 more. 2nd grade sheets print 7 to a page.

A few of the sentences, as the answer key corrects them:

Amara rinsed two cups of cherries for the pie.
Maya dried six dishes after dinner.
Many wishes were made over the birthday cake.

Fix it. Write the plural of the word in parentheses to complete each sentence. 8 sentences to fix per page.
Choose the word. Circle the letter of the correctly spelled plural. 10 questions per page.

Every version prints on US Letter or A4, with its answer key on the last page.

How to teach this

Sort practice words by family before mixing them: an -es day, an -ies day, a -ves day, then a mixed worksheet to test retention. The consonant + y versus vowel + y contrast (babies but boys) deserves its own explicit minute, since it's the one kids merge into a single wrong rule most often.

Watch for: The -es rule follows the sound: you can hear the extra beat in fox-es and bench-es. If you can hear it, spell it. Words ending in vowel + y just add -s: boys, days, keys. Only consonant + y changes to -ies.

Common questions about 3rd grade plural noun rules

Why does baby become babies but boy stays boys?: Look at the letter before the y. A consonant before y (baby, city, puppy) means the y changes to -ies. A vowel before y (boy, day, key) means plain -s. It's the one plural rule worth memorizing as a rule rather than by ear, because the sound doesn't give it away.
What are the -ves plurals?: A family of f-words trades f for -ves: leaf/leaves, wolf/wolves, shelf/shelves, knife/knives. Not every f-word does it (roofs, chiefs), so third graders learn the common -ves set as a list and treat the rest as regular.

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Aligned to Common Core L.3.1.b. Reviewed by the One more sheet team. Content version 241, updated October 2026.

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