The ancient Egyptians were either the first or one of the first ancient civilizations to divide a day into sections, so they could tell what time it was.
Around 3,500 BCE (a long, long time ago), the Egyptians used the shadows the giant stone obelisks cast on the ground to tell the time of day. Each obelisk was built to tell a story. But they worked very well as shadow clocks.
Later on, the ancient Egyptians invented the first portable timepiece. It was also a shadow clock, but you could carry it around with you. It was light weight, and about a foot long, maybe a little longer. It had a raised section in the middle. The rod was marked with 10 or 12 sections. To tell time, you pointed the end of the rod towards the east in the morning and towards the west in the afternoon. The raised center piece cast a shadow on the rod. Where the shadow fell on the markings would tell you what time it was. This creative invention is known as the ancient Egyptian shadow clock. Pretty clever!