Corrected sentence:
On a snowy day, the kids throw snowballs and build a snowman using a carrot for its nose.
Why this is good (easy steps):
- "On a snowy day," is a time phrase. We put a comma after it to show where the sentence starts.
- "The kids" is clear — it tells us which kids. You can also say just "kids," but "the kids" sounds a little nicer here.
- "Throw" and "build" are action words (verbs). They are in the right form for "kids."
- We use "its" to show the carrot belongs to the snowman. So say "its nose," not "the nose."
Short note: Your original sentence was mostly correct. This version just makes it a little clearer by adding "the" and using "its."
Try this: Write your own sentence about a sunny day using the same pattern: "On a sunny day, the kids play and make a picnic with a blanket on the grass."