O'clock is a way of telling the exact hour on a clock. We say "o'clock" when the minute hand (the long hand) points to the number 12 on the clock. When the minute hand points straight up to 12 ...

When the minute hand on a clock moves from one number to the next, it has moved 5 minutes. There are 12 numbers around a clock face, and each interval between the numbers is 5 minutes, so there ...