"Hyejin yah, come over to my house today? I can help you with Chemistry."

A smile played on Wheein's lips. I squeezed her hand in agreement.

"Tell your mum to make those creamy cheese puffs that I love? I haven't eaten them for a really long time."

When we reached Wheein's house, I greeted her parents politely. Her mother held a gentle, soft smile as she welcomed me. Her father was reading the newspaper, but he quickly stood up and ruffled my hair. I love Wheein's parents; they always showered me with warmth whenever I went over to their house. It was apparent that Wheein got her friendly and sweet nature from them.

As I expected, the aroma of freshly baked cheese puffs wafted through Wheein's room. I settled down comfortably on her squishy mattress and dragged my chemistry book out. Wheein pulled my lazy body to sit up.

She groaned and commented, "Let's get started, you can sleep 10 hours later."

Throwing her hair into a messy bun, she scavenged her bag and dug out all her worksheets and notes. Hardly feeling surprised, I smiled. This kid really put in effort for everything she did.

She started off, "To form a chemical formula, you have to know which elements belong to which group in the