Writing a Complete Sentence

Kindergarten
1st grade
CCSS L.K.1f
CCSS L.K.2a
CCSS L.1.1j

A complete sentence tells a whole idea. It has a who (someone or something) and a did what (what they do or are). It starts with a capital letter and ends with a period, question mark or exclamation point: The dog ran.

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The parts of a sentence

Every sentence needs two parts. The who part (the subject) names a person, animal or thing: The dog, My mom, I. The did-what part (the predicate) tells what they do or are: ran, likes pizza, is happy. Put them together and you have a sentence: My mom likes pizza.

A group of words missing one part is not a sentence. The big dog has a who but no did-what. Ran to the park has a did-what but no who. Young writers can check with two questions: Who? Did what? Then check the capital letter and the end mark.

Capital letter + who + did what + end mark.
The dog ran.

Kindergartners build sentences out loud and in shared writing, and capitalize the first word and I (L.K.1f, L.K.2a). 1st graders write and expand sentences of all four types (L.1.1j). Next: end marks and types of sentences.

Who + did what = sentence

Mix and match to build sentences.

Who (subject)	Did what (predicate)	Sentence
The cat	sleeps.	The cat sleeps.
My brother	kicked the ball.	My brother kicked the ball.
I	like apples.	I like apples.
The bird	sang a song.	The bird sang a song.
We	went to the park.	We went to the park.
The sun	is hot.	The sun is hot.

Once kids can write simple sentences, show them how to expand: add when, where or how. The cat sleeps becomes The cat sleeps on my bed every night.

Sentence or not?

Each one is labeled. The fixes are shown.

Sentence: The dog ran.
Sentence: I can jump.
Not a sentence: The big red ball. (no did-what) → The big red ball bounced.
Not a sentence: Swims in the pond. (no who) → The duck swims in the pond.
Missing capital: my cat is soft. → My cat is soft.
Missing end mark: We ate lunch → We ate lunch.
Lowercase i: i like dogs. → I like dogs.
Question: Can you play?
Exclamation: I won!
Expanded: The dog ran fast to the gate.

Read a sentence aloud. If it sounds like a whole idea and answers who and did what, it's a sentence.

How to teach complete sentences

Five short steps, about 10 minutes each.

Say it first. Have your child say the sentence out loud before writing.
Count the words. Tap or draw a line for each word, then write.
Check who and did what. Point to each part.
Capital and end mark. Circle the capital, check the period.
Make it longer. Add where, when or how.

Common mistakes and how to fix them

Mistake	Why it happens	How to fix it
Writes only a few words like the cat	Missing the did-what.	Ask: what did the cat do?
Forgets capital letters	Not a habit yet.	Check the first letter every time.
Leaves off the period	Thinks the idea is finished.	Read it aloud; stop at the dot.
Writes lowercase i	Forgetting the rule.	I is always a capital.

Practice: complete sentences quiz

10 questions. Your child can tap the speaker to hear a question read aloud. The first try on each question counts toward the score.

1.Which is a complete sentence?

Show answer
The dog ran.
2.A sentence starts with a...

Show answer
capital letter.
3.What does a telling sentence end with?

Show answer
A period.
4.What is missing? Swims in the pond.

Show answer
The who.
5.What is missing? The little bird

Show answer
The did-what.
6.Tap the who part.

.

Show answer
Grandma.
7.Which sentence is written correctly?

Show answer
I like dogs.
8.Tap the did what word.

.

Show answer
jumped.
9.Which is a longer, better sentence?

Show answer
The cat sleeps on my bed.
10.What does a question end with?

Show answer
A question mark.

Writing a Complete Sentence worksheet (free PDF)

Page 1 of the writing a complete sentence worksheet: circle complete sentences, fix capital letters and periods, and write sentences from pictures

Writing a Complete Sentence Worksheet, Kindergarten–1st grade

Circle complete sentences, fix capitals and periods, match who and did-what parts, and write your own sentences. Prints on US Letter paper, with an answer key.

Download the PDF

Try it at home

Say it first: say the sentence before writing.
Who and did what: point to each part.
Caption photos: write one sentence under a picture.
Grocery sentences: "We need milk."
Make it longer: add where or when.

What comes next

Next: how-to writing. Related: capital letters, end marks and types of sentences.

Practice with a game

Free, no sign-up, and they work on phones, tablets and computers.

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Last reviewed: November 11, 2026

Questions parents ask

What is a complete sentence for kids?

A group of words that tells a whole idea: it has a who (subject) and a did-what (predicate), starts with a capital letter and ends with an end mark.

What are the parts of a sentence?

The subject (who or what the sentence is about) and the predicate (what they do or are).

What grade learns complete sentences?

Kindergarten builds sentences with help (L.K.1f); 1st grade writes and expands them (L.1.1j).

What's a sentence fragment?

A group of words missing a part, like 'The big dog' or 'Ran fast.'

How do I help my child write sentences?

Have them say the sentence aloud first, count the words, then check for a capital and a period.