After a long day of biking, rollerblading, and hiking the students were exhausted.

Is this a proper sentence and correct punctuation?

It's a proper sentence, but it needs a comma after "hiking."

Thank you!

You're welcome.

Yes, the sentence "After a long day of biking, rollerblading, and hiking, the students were exhausted" is a proper sentence with correct punctuation.

To determine if a sentence is proper and has correct punctuation, you can follow these steps:

1. Check for a subject and a verb: The sentence has a subject ("students") and a verb ("were"), so it meets this requirement.
2. Look for a complete thought: The sentence expresses a complete thought, as it conveys a clear message about the students being exhausted after their activities.
3. Verify capitalization: The first word of the sentence, "After," is capitalized, which is correct.
4. Check for ending punctuation: The sentence ends with a period, which is appropriate for a declarative sentence that is not a question or an exclamation.

By following these steps, you can determine if a sentence is proper and correctly punctuated.