When two materials rub together, one gains extra charge. This is the triboelectric effect. Rubbing wool on plexiglass builds up a negative charge on the plate. That charge pulls the lightweight cereal pieces upward through the air.

Rubbing styrofoam with a wool sock transfers charge from one surface to the other — the friction leaves the styrofoam with a strong negative charge. When you set an aluminum pie plate on top using a pen handle, that charge repels electrons on the plate's surface. The imbalance builds until, in a darkened room, a small visible spark jumps from the plate's edge to your fingertip.

The triboelectric effect depends on the materials involved, not on how they look. Rubbing a balloon against wigs of different hair colors — black, brown, blond, and red — tests whether color changes how much charge builds up. All four hair colors pick up nearly the same number of paper pieces, showing that charge transfer comes from the material itself, not its pigment.

Not all materials transfer charge equally — the triboelectric effect varies depending on what surfaces rub together. Rubbing an inflated balloon across hair, polyester, carpet, cotton, nylon, and ceramic tile, then counting the paper squares that stick, makes those differences visible. Hair creates the most static by far, while ceramic tile produces none at all.

The triboelectric effect is why you sometimes get a shock stepping out of a car. Static charge forms when two surfaces rub together, and different material pairs transfer different amounts of charge. Rubbing a balloon against clothing fabrics on both a fabric seat and a leather seat reveals which combinations produce the most static buildup.