The axis of Earth is an imaginary line passing through Earth that Earth rotates around. The diagram shows three possible orientations of Earth’s axis. The direction of the axis is in reference to Polar, commonly called the North Star.
Diagram #1 best represents the orientation of Earth’s axis. A more accurate drawing would have the axis tilted at about 23 o in reference to the Sun. This tilt causes different seasons on Earth.
Diagram 1 shows Earth rotating from west to east, thus every part of the Earth experiences a day and night period as it faces, then rotates away from the Sun. About half of the Earth from north to south is lighted when it faces the Sun, while the opposite half facing away from the Sun is in the dark.
This diagram aligns with the following Texas Science Standards for 5th grade.
Draw or develop a model that represents how something works.
Demonstrate that Earth rotates on its axis once approximately every 24 hours causing the day/night cycle and the apparent movement of the Sun across the sky.
Diagram 2 shows the axis passing through the Earth from west to east, and the rotation from south to north. Notice that the west side of the Earth would always face the Sun and thus would always be lighted. The opposite half of the Earth would never have nighttime.
Diagram 3 is interesting. I am not sure about the direction since in geometry it is called the Z axis. But since it is an imaginary diagram, I am just calling it “?.” Spacial orientations and motions are not my best thing. I have problems putting together simple flat jig-saw puzzles. So trying to imagine how motion around this axis has my mind spinning. But I can say that all the surface of Earth would experience day and night periods and the Sun would appear to move across the sky.