When should students use "so" instead of "but"?

So means the second half happened because of the first: "It rained, so we went inside." But means the second half pushes against the first: "It rained, but we stayed outside." Have your student ask, is this a result or a fight? The answer picks the word.

Is "because" a coordinating conjunction?

No; because is a subordinating conjunction, which works differently in a sentence. The coordinating set third graders drill is and, but, or, so. Because gets its own worksheets under subordinating conjunctions.

3rd grade coordinating conjunctions

3rd grade coordinating conjunctions worksheets

The coordinating conjunctions (and, but, or, so) each signal a relationship: addition, contrast, choice, or result. Third graders choose the one that fits and start using them to build compound sentences.

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

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 joining word that fits the sentence.

The tuba looks heavy, Amara carries it with one arm. so · but · or
Answer: but
Nora practiced her free throws every morning, her scores kept climbing. but · or · and
The wind blew hard, the leaves danced down the street. and · or · but

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 95 sentences, 10 to a page. All 60 of 2nd grade's sentences are here too, plus 35 more. 2nd grade sheets print 8 to a page.

A few of the sentences:

Priya tried to catch the ball, but it bounced away.
The muffin smelled great, but it was too hot to eat.
We built a snowman, but the sun melted it by lunch.

Choose the word. Circle the letter of the joining word that fits the sentence. 10 questions per page.

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

How to teach this

Add "so" as the result word: it answers "what happened because of that?" The reliable routine is to read the first half, read the second half, and name the relationship out loud (same direction, opposite direction, choice, or result) before picking. Students who name the relationship first almost never miss.

Watch for: The conjunctions aren't interchangeable: 'I fell and I laughed' tells a different story than 'I fell, but I laughed'. Because is a joining word too, but it isn't a coordinating conjunction. The core set here is and, but, or, so, yet.

Common questions about 3rd grade coordinating conjunctions

When should students use "so" instead of "but"?: So means the second half happened because of the first: "It rained, so we went inside." But means the second half pushes against the first: "It rained, but we stayed outside." Have your student ask, is this a result or a fight? The answer picks the word.
Is "because" a coordinating conjunction?: No; because is a subordinating conjunction, which works differently in a sentence. The coordinating set third graders drill is and, but, or, so. Because gets its own worksheets under subordinating conjunctions.

Related worksheets

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

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