BGCSE key terms

The side of a right-angled triangle that lies opposite the right angle. It is always the longest side, and its length can be calculated using Pythagoras' theorem.

A measure of how steep a straight line is on a graph, found by dividing the vertical change by the horizontal change between two points on the line.

A number between 0 and 1 that expresses how likely an event is to happen, where 0 means the event is impossible and 1 means it is certain.

The average of a set of numbers, worked out by adding all the values together and then dividing the total by the number of values in the set.

A direction measured clockwise from north and written as a three-figure angle, used to describe the position of one point from another.

A figure of speech that compares two different things using the words 'like' or 'as', for example 'as brave as a lion'.

A figure of speech that describes one thing as if it were another, without using 'like' or 'as', for example 'the classroom was a zoo'.

A conclusion a reader reaches by combining clues in a text with what they already know, instead of being told the information directly by the writer.

The choice of words and level of formality a speaker or writer uses, which changes according to the audience, purpose and situation.

The sentence, usually at the start of a paragraph, that states the main idea which the rest of the paragraph will develop and support.

The rate at which an object's velocity changes with time, including speeding up, slowing down or changing direction. It is measured in metres per second squared.

The bending of light or another wave as it passes from one material into another, caused by a change in the speed of the wave.

The electrical potential difference between two points in a circuit, which pushes electric charge around the circuit. It is measured in volts.

The energy that an object has because it is moving. The amount depends on the object's mass and on how fast it is travelling.

The amount of a substance that contains 6.02 x 10^23 particles. It links the mass of a substance to the number of particles it contains.

The number of chemical bonds that an atom of an element can form, usually linked to the number of electrons it needs to gain, lose or share.

The breaking down of an ionic compound, either melted or dissolved in water, by passing an electric current through it.

One of two or more atoms of the same element that have the same number of protons but different numbers of neutrons in their nuclei.

The movement of water molecules through a partially permeable membrane from a region of higher water concentration to a region of lower water concentration.

The process by which green plants use light energy to combine carbon dioxide and water into glucose, releasing oxygen as a by-product.

A protein that speeds up a chemical reaction in a living organism without being used up itself. Each enzyme works best at a particular temperature and pH.

The keeping of a steady internal environment inside the body, such as constant temperature, blood sugar and water levels, despite changes outside the body.

Evidence about the past produced at the time being studied, such as letters, photographs, official records or objects, rather than a later account of events.

The control by one country over another territory and its people, often for economic gain, involving settlement, administration and far-reaching cultural change.

A strong sense of belonging to a nation and the belief that its people should govern themselves, which drove many independence movements in Africa.

A territory that keeps its own ruler and laws but is protected and partly controlled by a stronger state. Botswana was administered in this way from 1885.

The whole area of land drained by a river and its tributaries, bounded by higher ground called the watershed.

The wearing away and removal of rock and soil by natural forces such as flowing water, wind, ice or waves.

The growth in the proportion of a country's population living in towns and cities, often caused by people moving from rural areas.

The total value of goods and services produced within a country in a year, used as a measure of the size of its economy.

Development that meets the needs of people today without using up resources or damaging the environment in ways that harm future generations.

A measure combining average income, life expectancy and education to compare how well different countries provide for the needs of their people.

Economic activity that is not registered or taxed, such as street trading and casual labour, which provides income for many people in developing countries.

Setswana proverbs: short traditional sayings that carry advice or wisdom and are often used to teach a lesson or settle an argument.

A Setswana praise poem that honours a person, clan or animal by describing its qualities and deeds in vivid, rhythmic language.

Setswana folktales: traditional stories passed on by word of mouth rather than written down, often used to teach children about behaviour and customs.

A drawing method that shows a three-dimensional object as separate front, top and side views, each drawn flat so that measurements can be read accurately.

A plan showing the money that a person, family or business expects to receive and how it will be spent over a set period.

The immediate, simple help given to an injured or ill person before professional medical care is available, aimed at keeping them safe and stable.

A first working model of a product, made to test the design and find problems before the final version is manufactured.