While teaching me magnetism, my teacher told me about the spin of an electron. He told me that the spin of .5 means that if we rotate the electron twice counter-clockwise on its axis, we would have the same face(picture) of the electron. And if we rotate an electron of -0.5 spin twice in the opposite direction, we would have the same face. But if rotate it only once(360⁰), we would not get the same face/picture of an electron.

How can this be possible? Or am I just making a mistake somewhere? A simple explanation would be greatly appreciated for I am only a tenth grader.