The Missing Half Hour

I am visually impaired, and basically cannot see anything. This day, I went on a trip with my teacher and several other friends. After finishing lunch, we planned to first visit the clock tower, then go to the cinema to watch a movie. Inside the clock tower, I asked my teacher "What time is it", and my teacher said "2 PM". After that, the teacher led me to the front of the clock, told me to stand still and not move. He only led me away after a while. Suddenly, I heard a woman loudly remind us, "It's already 2:30 PM, the movie is about to start, hurry to the cinema". We quickly walked out of the clock tower, got in the car, and rushed to the cinema. When we arrived at the cinema and sat down inside, I asked my teacher sitting next to me "What time is it now, when does the movie start". My teacher said, "It's 2:30 PM now, the movie starts at 3 PM". I was confused at first, but when I thought about the teacher sitting next to me, I instantly realized what happened.