Foundations

Distinguish part-to-part ratios, fractions of a whole and rates with units. Scale quantities together, compare unit rates, and explain when a relationship is proportional. Check zero cases, starting amounts and whether a result fits its context.

Describe a quantity as a numerical value with a unit, and distinguish its physical kind from its dimension. Build length, area, volume and rate units, check meaningful combinations, and separate exact unit relations from measurement uncertainty.

Convert quantities with exact unit ratios, track cancellation through compound units, and apply the correct powers to area and volume. Distinguish temperature readings from differences, check dimensions and context, and retain measurement uncertainty when reporting.

Distinguish exact model values, rounded approximations and estimates from measurements. Declare the rounding rule, preserve information through calculations and unit changes, and interpret resolution, precision, accuracy and the stated uncertainty type without turning a report’s digits into guaranteed bounds.

Read a graph’s quantities, units, ticks and context before judging its visual impression. Calculate differences, reference-based percentages and interval rates from the represented values; distinguish legitimate zoom from distorted spacing; and keep samples, interpolation, missing information, uncertainty and causal explanations separate.

Choose the physical quantity you want to investigate, specify the point, event or location involved, and explain how a reading relates to that quantity.

Build an inspectable physics record, test and revise a bounded cart model, preserve processing history, and plan findable data with appropriate sharing conditions.

c denotes the speed of light in vacuum. Its numerical value is fixed exactly in SI units.

h denotes the Planck constant. Its numerical value is fixed exactly in SI units.

ΔνCs denotes the unperturbed ground-state hyperfine transition frequency of caesium-133. Its numerical value is fixed exactly in SI units.

In a Euclidean right triangle, squared leg lengths sum to the squared hypotenuse length.

A confidence level describes repeated-sampling coverage of an interval procedure.

Seven named base units organize the SI quantity system.

Prefix symbols specify decimal scale factors.

Connect a result to a reference through documented calibrations.

Combine input uncertainty through a measurement model.

Use dimensions to detect impossible quantity equations.

Current measures charge crossing a chosen surface per unit time.

The elementary charge has an exact SI numerical value.

The Boltzmann constant has an exact SI numerical value.

The mole is linked to a specified number of entities.

A specified frequency fixes the photometric SI reference.

The mole counts specified entities using the exact Avogadro constant.

Relate indications to standards, then infer measurement results.

The classification describes how a component is evaluated.

A coverage factor scales standard uncertainty to a reported interval.

Shared input variation belongs in the joint uncertainty description.

Specify how input quantities determine the measurand.

Sample the joint input model to approximate the output distribution.

Precision depends on which measurement conditions are held or changed.