How can I refuse that male classmate?

My classmate is also my best friend, and your situation is exactly the same.

I understand you, because I am a junior high school student like you.

I think you should be more tactful. You tell him, "You're fine, but it's time to study. I don't want to date, I just want to study! If possible, I hope we can become good friends! " This will not make him sad, nor will it create a distance between you! I sincerely wish you all!