Magnets attract iron but have no noticeable pull on wood, plastic, or glass.

The longer version

Iron belongs to a small group of materials whose atoms act like tiny aligned magnets. Inside such a material the electrons line up in regions that reinforce one another, so an external magnet can pull the whole piece toward it. Wood, plastic and glass have electrons arranged in pairs that cancel out.

Those cancelled arrangements respond only extremely weakly, far too little to notice. Metals such as nickel and cobalt behave like iron, while most everyday objects show no visible response at all. Even a strong magnet passes right by a plastic cup without any measurable tug.

Where this entry sits

Everyday physics and chemistry hide small wonders in plain sight, from kitchen reactions to the light in the sky. These short facts explain matter, energy, electricity, magnets, sound, and the simple units we use to measure the world. The full list sits on the Science and Physics page, where every entry is listed in order.