Key terms & definitions

Worth that something has in itself, regardless of whether it is useful to humans.

The stage when a product is launched onto the market and sales are usually low and grow slowly.

A personality type characterised by being shy or quiet, thoughtful and enjoying time alone.

A storyteller who openly comments on events or characters and may address the reader directly.

Data of the correct data type which should be rejected by a computer system.

A property that remains unchanged after a transformation or combination of transformations.

A property or point that remains unchanged after a transformation or sequence of transformations.

A line that maps onto itself. Its individual points need not all stay fixed, although every point on a mirror line stays fixed under reflection in that line.

A point that finishes in exactly the same position after a transformation or sequence of transformations.

A feature or quantity that remains unchanged under a transformation.

A developmental stage within a fixed sequence that, according to Piaget, all children pass through.

A story imagining an invasion of a country, often exposing fears about military preparedness and national security.

A species introduced outside its natural range that spreads and causes harm to the environment.

Forceful verbal attack or denunciation of a person, behaviour or social practice.

The creation of a new idea, product or technology that did not previously exist.

An itemised record of possessions at a particular time.

A list recording items and their quantities, often used to manage supplies or possessions.

The calculator function $\cos^{-1}$ used to find an angle from its cosine value.

A function that reverses another function, taking an output back to its original input.

The notation for the inverse of the function $f$; it is read as “$f$ inverse of $x$”.

A relationship in which one quantity changes by the opposite factor to another, so their product stays constant.

A relationship in which multiplying one quantity by a factor causes the other quantity to be divided by that factor.

An operation that reverses another operation, such as subtraction reversing addition and division reversing multiplication.

An operation that reverses another operation, such as division reversing multiplication.

An operation that reverses another operation, such as subtraction reversing addition.

Operations that undo one another, such as addition and subtraction or multiplication and division.

A relationship in which one quantity is proportional to the reciprocal of another quantity.

A relationship in which multiplying one quantity by a factor divides the other by that factor.

A relationship of the form $y=k/x$, where the product $xy$ is constant.

A relationship in which one quantity increases in the same ratio as the other decreases, so their product remains constant.