Only certain materials are attracted to magnets. Iron, nickel, and cobalt are the three common magnetic metals — a magnet will pull them toward it. Most other materials, including wood, plastic, glass, copper, and aluminum, are not magnetic at all. You can test any object with a magnet to find out. Steel is magnetic because it contains iron. Knowing which materials are magnetic is useful for sorting, building, and understanding how everyday devices like refrigerator magnets and compasses work.
Give each student a magnet and a tray of objects: paper clips, coins (some magnetic, some not), aluminum foil, a wooden block, a plastic spoon, a steel washer, a copper wire, and a rubber band. Have them predict which ones will be attracted to the magnet, then test and record results. Discuss patterns — most magnetic items contain iron.
Pick up a magnet and hold it near a paper clip. The paper clip jumps up and clings to the magnet. Now hold the same magnet near a wooden pencil. Nothing happens. Why does the magnet attract some things and completely ignore others? The answer comes down to a property called magnetism — and only certain materials have it.
The three common magnetic metals are iron, nickel, and cobalt. If an object contains one of these metals, a magnet will attract it. Steel paper clips are magnetic because steel is an alloy that contains iron. The door of your refrigerator is magnetic for the same reason — it is made of steel. Nickel coins (real nickel ones, not just coins named "nickel") are magnetic because they contain the metal nickel.
Here is the surprise that trips up many people: most metals are not magnetic. Copper, aluminum, gold, silver, tin, and lead are all metals, but a magnet does not attract any of them. You can hold the strongest magnet in the world next to a copper pipe and nothing will happen. Being shiny and metallic does not make something magnetic. Only those three specific metals — iron, nickel, and cobalt — respond to magnets.
Non-metal materials are never magnetic. Wood, plastic, glass, rubber, paper, and fabric all ignore magnets completely. This makes the magnet test a useful tool for identifying what something is made of. If a mystery object sticks to a magnet, you know it contains iron, nickel, or cobalt. If it does not, you have ruled those out.
Magnetism is used in many everyday devices. Refrigerator magnets stick to the steel door because steel contains iron. Compasses work because a magnetized needle naturally points toward Earth's magnetic north pole. Recycling centers use giant magnets to pull steel cans out of mixed waste — the steel sticks while the aluminum cans, plastic bottles, and paper fall right through. Even your headphones and speakers contain magnets that help turn electrical signals into sound. Magnetism might seem like a simple property, but it is everywhere once you start looking.