NSES Content Standard Unifying Concepts and Processes:   Systems, order, and organization  Grades K-12, page 117  Order--the behavior of units of matter, objects, organisms, or events in the universe--can be described statistically. Probability is the relative certainty (or uncertainty) that individuals can assign to selected events happening (or not happening) in a specified space or time. In science, reduction of uncertainty occurs through such processes as the development of knowledge about factors influencing objects, organisms, systems, or events; better and more observations; and better explanatory models.

Benchmark 4E The Physical Setting: Energy Transformations
Heat energy in a material consists of the disordered motions of its atoms or molecules. In any interactions of atoms or molecules, the statistical odds are that they will end up with less order than they began--that is, with the heat energy spread out more evenly. With huge numbers of atoms and molecules, the greater disorder is almost certain.

Benchmark 9D The Mathematical World: Uncertainty
How probability is estimated depends on what is known about the situation. Estimates can be based on data from similar conditions in the past or on the assumption that all the possibilities are known.

Benchmark 9D The Mathematical World: Uncertainty
Probabilities are ratios and can be expressed as fractions, percentages, or odds.

Benchmark 9D The Mathematical World: Uncertainty
The larger a well-chosen sample is, the more accurately it is likely to represent the whole. But there are many ways of choosing a sample that can make it unrepresentative of the whole.

Benchmark 9D The Mathematical World: Uncertainty