It sounded very much like the moving of chairs. You peeped into a corner which was blocked by a pile of soil. 

You saw Changjo sitting on a cemented bench alone in a napping position.

You: Ya! Changjo! Why did you hide here?! Do you know how hard I tried to find you?! God damn it! *you went forward and hugged him tightly and was relieved that he was alright* I almost cried and was worried sick you!... Jerk!

ChangJo: I'm sorry... I just needed to be alone for a while. Thanks for taking time to look for me though.

You: Don't ever do that again. Let's go back to class. I lied about going to the toilet and I was told to go back fast.

ChangJo: Okay.