Did you ever notice your shadow at different times of the day? Shadows change as the day goes on.
In the morning the sun makes long shadows. In the middle of the day, the sun seems to be right over your head and your shadow is very, very small. As the sun goes down in the afternoon, shadows grow very long again. But the long afternoon shadows fall in a different direction from the long morning shadows.
Long, long ago people told time by the shadows. Put a piece of paper in the sunlight. Stand a pencil in a spool in the middle of the paper. The shadow of the pencil will fall on the paper and move as the day goes on. Use a watch and every hour marks the place where the shadow falls. Now your paper is a sundial(通过太阳辨别时间的日规)and you can tell every sunny day. Just look at your paper sundial and see where the shadow falls.