Why are both answer choices sometimes real words?

That's the grade-3 step: careful and careless both exist, so the sentence has to be read for meaning. A child who spilled juice was careless; one holding glass should be careful. Context does the deciding, which is precisely the skill worth practicing.

Why does happy become happily instead of happyly?

Words ending in a consonant plus y trade the y for an i before most suffixes: happy, happily; easy, easily (never before -ing: crying). It's one of the most dependable spelling rules in English, and meeting it inside real words beats memorizing it as a rule alone.

3rd grade suffixes

3rd grade suffixes worksheets

Third graders read suffixes as meaning clues and start weighing pairs like careful and careless, where both are real words and only the sentence tells you which fits. Spelling shifts appear too: happy drops its y in happily.

Free printable PDF worksheet, aligned to Common Core L.3.4.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 get

Circle the letter of the word with the correct suffix.

The peacock spread its tail. glorious · gloriness · gloriment
Answer: glorious
The committee chose paper lanterns. decoratement · decorateness · decoration
The for the class pizza is due Friday. payment · payness · payable

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 120 sentences, 10 to a page. All 60 of 2nd grade's sentences are here too, plus 60 more. 2nd grade sheets print 8 to a page.

Some of the answers:

teachersingerchewybouncystillnessimprovementdangerousnervousconstructionenjoyment

Choose the word. Circle the letter of the word with the correct suffix. 10 questions per page.

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

How to teach this

The careful/careless items are the heart of this grade: both are real, so the sentence must be read for its story. When your child picks wrong, don't correct the word; reread the sentence and ask what it's trying to say. Note the spelling changes out loud when they appear, but keep the focus on meaning.

Watch for: -ful and -less are opposites on the same base: hopeful means full of hope, hopeless means without it. A suffix can change a word's job in the sentence: teach is an action, teacher is a person.

Common questions about 3rd grade suffixes

Why are both answer choices sometimes real words?: That's the grade-3 step: careful and careless both exist, so the sentence has to be read for meaning. A child who spilled juice was careless; one holding glass should be careful. Context does the deciding, which is precisely the skill worth practicing.
Why does happy become happily instead of happyly?: Words ending in a consonant plus y trade the y for an i before most suffixes: happy, happily; easy, easily (never before -ing: crying). It's one of the most dependable spelling rules in English, and meeting it inside real words beats memorizing it as a rule alone.

Related worksheets

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Aligned to Common Core L.3.4.b. Reviewed by the One more sheet team. Content version 241, updated August 2026.

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