Corrected sentence
Good version: A balloon is filled with hot air, and it floats up, up, up into the sky!
Shorter option: A hot-air balloon rises into the sky.
Why this is better (step by step)
- Comma before "and": When you join two full ideas (clauses) with "and," put a comma before "and." Example: "A balloon is filled with hot air, and it floats..."
- Use a clear subject for the second part: Add "it" so the sentence shows who is doing the action: "and it floats..."
- Choose the best verb: "pops up" sounds like a quick, small jump. Balloons usually "float up" or "rise," which fits better.
- Repeating words for excitement: "up, up, up" is fine to show excitement. Put commas between the repeated words and end with an exclamation mark if you want excitement.
Extra examples
- Fun and simple: "The balloon fills with hot air and rises into the sky."
- Very excited: "The balloon floats up, up, up into the bright blue sky!"
So, the best fix is: A balloon is filled with hot air, and it floats up, up, up into the sky!