Quantum uncertainty: what to teach?

Abstract We present a new secondary school teaching method of quantum uncertainties two-state systems. Intending to be material teachable in schools, only systems described by real numbers can considered. An elementary argumentation based on statistics leads the identification uncertainty physical quantity such with standard deviation two random variables. provide qualitative picture state-dependence uncertainty, leading pictorial representation form four petals flower. When considering product essentially different quantities we conclude that general feature: “if measurement one is certain, other remains uncertain”, cannot faithfully expressed means an inequality, has no lower bound from zero. The application techniques used materials for physics exact formula valid any system numbers, full harmony picture. compare case celebrated Heisenberg position-momentum relation and show these are both specific facets, but inequality. latter hardly provides hint approach worth schools also relation, even if not part curriculum.