Stern–Gerlach experiment

The Stern–Gerlach experiment is a physics experiment that shows that beams of particles don't all act the same. To do the experiment, you shoot a beam of particles (like atoms or molecules) through a magnetic field. Normally the beam would just carry on in a straight line, but if the particles have something called "spin" then they will get pulled around by the magnetic field and change direction. It's like when you put a compass in a magnet - the needle will point in a different direction because it has spin.