You can find a stump in the forest and tell the direction according to its annual rings, because its annual rings are always wide in the south and narrow in the weak side; You can observe an independent tree with lush foliage on the south and sparse foliage on the north. You can tell the direction according to the ant's cave. Because most of the female ants' holes face south; Where there are many rocks, you can also find an eye-catching rock to observe. The mossy side of the rock is the north side, and the dry and bare side is the south side. On a starry night, we can tell the direction according to the stars: first find the Big Dipper in the sky, along its "spoon handle", find the sixth and seventh stars, and connect the two stars into a straight line according to the mathematical principle of determining a straight line at two points, and find a brighter Polaris on the extension of this straight line. From the "spoon handle" to the brighter Polaris, it just points out the direction from south to north. If it is in winter, the part of the snow that is difficult to melt always faces north because of the sunlight. In addition, there are temples, pagodas, and ordinary houses, most of which face south, while the gate of Islamic mosque opens to the east. In addition, Polaris is used to judge the direction, the natural wind direction in each season, the surface morphology of desert dunes and so on.