The Boogie Board sandwiches trillions of liquid crystals—tiny molecules that arrange themselves in spirals—between two plastic sheets. At rest, the screen appears dark because the spirals lie in a way that lets outside light pass through to the black plastic below. But direct pressure forces the spirals to stand upright. Light then bounces off them, naturally creating a bright whitish color, no energy-hogging lamp needed. The image stays put without power, unlike in a traditional LCD, because polymers mixed in with the liquid crystals help keep them in place. To erase, you press a button that sends a charge between the plastic sheets (which are coated with conductive film) and re-scatters the spirals.