Third Grade · Writing · week 4

Compound Sentences with And, But, So

Combine two complete sentences into one compound sentence using a comma plus and, but, or so.

A compound sentence joins two complete sentences into one, using a comma and a small connecting word: and, but, or so. Each half must be a complete sentence all by itself.

Use AND to join two similar or matching ideas. Use BUT to join two ideas that contrast or surprise. Use SO to join a reason with a result.

The pattern is: complete sentence + comma + and/but/so + complete sentence. Forgetting the comma is the most common mistake, so always check for it.

📋 For the teacher
Teach it (10–15 min):
  • Say each half of a compound sentence separately first, and ask "could this stand alone as its own sentence?" -- if yes on both sides, a comma plus and/but/so can join them.
  • Have your child sort a small set of sentence pairs into "would use and," "would use but," and "would use so" piles before writing anything down.
  • Watch for a common error: joining two sentences with just a comma and no and/but/so -- gently point out the missing connecting word.
  • Keep both halves short and clear this week; the comma and connecting word are the whole focus.
Talk about it:
  • When would you use "but" instead of "and" to join two sentences?
  • What goes right before and, but, or so in a compound sentence?
  • Can you think of a compound sentence about your day using "so"?

Mastery looks like: They correctly join two complete sentences with a comma plus and, but, or so, choosing the connecting word that matches the relationship between the ideas.

Common stumbles: Leaving out the comma before the connecting word; joining two sentences with only a comma and no and/but/so.

See it visually

Interactive, spoken-aloud tools that show this idea in motion.

Sentence TypesJoin clauses with and, but, because → compound & complex sentences.try →Sentence BuilderDrag word tiles into a real sentence, with a capital and end mark.try →Punctuation PowerThe same words as a statement, a question, or a shout — hear it change.try →
Homework for this lessonType it, write it with a stylus, or print it for pencil & paper.open →
Records attendance + 15 min of Writing for this learner.
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