The school campus is very large, and students basically go to class by bike. Once riding a bike on the main road, a buddy and I drove in the opposite direction. When they approached me, they held out their hands to me. I was nearsighted that day and didn't wear glasses. Seeing someone reaching for me from a distance, I thought it was a classmate I knew. It's impolite to ignore it, so I changed a one-handed handle, warmly reached out to him and gave him a high five. The child's expression froze immediately, he didn't hold the handlebar firmly and almost fell down. I didn't know why he was so excited. I think he may be greeting the person behind me. Maybe I have the wrong person. Later, I learned that you have to reach out when you turn by bike.