If you were going to spend the time to teach someone how to tell time, you would likely explain that there are 24 hours in a day, divided into (2) twelve-hour segments with AM coming before PM, each of those hours divided into 60 minutes, and each minute into 60 seconds. Once they understood this framework, you might then show them a clock, teaching them that the small hand identifies the hour and the long hand identifies the minute, and through this explanation your student would walk away with an understanding of how to tell time.