المصطلحات
كل مصطلح يقابله طالب من الصف الأول إلى العاشر أو في GCSE أو SAT، مُعرَّفاً في جملة واحدة.
الإجابة باختصار
معجم عملي لرياضيات المدرسة وعلومها ولغتها الإنجليزية ولنظام الامتحانات نفسه. كل مدخل يقدّم جملة دقيقة واحدة يستطيع الطالب استخدامها، ومثالاً محلولاً، والموضع الذي يظهر فيه المصطلح أول مرة.
A
- Absolute valueThe absolute value of a number is its distance from zero on the number line, so it is never negative: |−7| and |7| are both 7.
- AccelerationAcceleration is the rate of change of velocity — the change in velocity divided by the time it takes — measured in metres per second squared.
- Active transportActive transport is the movement of substances across a cell membrane against the concentration gradient, using energy released by respiration.
- Adaptive testingAdaptive testing is computer-based testing in which the difficulty of later questions is chosen from how the candidate answered earlier ones, so two candidates sit different questions.
- Algebraic expressionAn algebraic expression is a combination of numbers, variables and operations with no equals sign, such as 3x + 2.
- AlleleAn allele is one of the different versions a gene can come in, sitting at the same place on a chromosome as the others.
- AlliterationAlliteration is the repetition of the same opening consonant sound in words that sit close together, judged by sound rather than by spelling.
- AmplitudeAmplitude is the maximum distance a point on a wave moves away from its undisturbed rest position.
- AnaphoraAnaphora is the deliberate repetition of the same opening words in a run of successive clauses, sentences or lines of verse.
- Angle of elevation and angle of depressionThe angle of elevation is the angle from the horizontal up to your line of sight; the angle of depression is the angle from the horizontal down to it.
- AntecedentAn antecedent is the noun or noun phrase that a pronoun refers to, so that the pronoun's meaning depends entirely on it.
- Arithmetic meanThe arithmetic mean is the total of a set of values divided by how many values there are.
- Arithmetic sequenceA sequence in which each term is found by adding the same fixed number, called the common difference, to the term before it.
- AsymptoteA straight line that a curve draws ever closer to as it runs out towards infinity, without ever meeting it.
- Atomic numberThe atomic number is the number of protons in the nucleus of an atom, and it determines which element that atom is.
- Axis of symmetryThe axis of symmetry of a parabola is the vertical line through its turning point, which reflects one half of the curve exactly onto the other.
B
- BiomeA biome is a large-scale region of the Earth defined by its climate and by the community of plants and animals that the climate supports.
- Box plotA box plot is a diagram of five values from a data set — the minimum, lower quartile, median, upper quartile and maximum — drawn against a single scale.
C
- CatalystA catalyst is a substance that speeds up a chemical reaction by lowering its activation energy and is not used up or chemically changed by the reaction.
- ChlorophyllChlorophyll is the green pigment inside chloroplasts that absorbs light energy, mostly red and blue, and makes that energy available for photosynthesis.
- ChordA chord is a straight line joining any two points on the circumference of a circle; the longest chord in a circle is its diameter.
- ChromatographyChromatography separates the substances in a mixture by how far each one travels through a stationary material while a moving solvent carries it along.
- ChromosomeA chromosome is one long, coiled molecule of DNA in the nucleus of a cell, carrying hundreds or thousands of genes along its length.
- ChronologyChronology is the ordering of events by the time at which they occurred, together with the system of dates used to fix them.
- CoefficientA coefficient is the number multiplying a variable in a term, such as the 5 in 5x².
- Common differenceThe fixed amount added to each term of an arithmetic sequence to get the next one, found by subtracting any term from the one that follows it.
- Common ratioThe fixed number each term of a geometric sequence is multiplied by to give the next one, found by dividing any term by the one before it.
- Composite functionA function formed by feeding the output of one function into another, written fg(x), which means apply g first and then f.
- Composite numberA composite number is a whole number greater than 1 with more than two factors, meaning it can be written as one smaller whole number multiplied by another.
- Concordance tableA concordance table pairs scores on two different tests that measure similar things, showing which score on one corresponds in standing to a given score on the other.
- Conditional probabilityConditional probability is the probability that one event happens given that another has already happened, calculated from the reduced set of outcomes still possible.
- CongruenceTwo shapes are congruent when they are the same shape and the same size, so one can be placed exactly on the other by turning, sliding or flipping it.
- Contour lineA contour line is a line on a map that joins all the points which are at the same height above sea level.
- Correlation and causationCorrelation is two quantities moving together in a pattern; causation is one of them making the other change, which correlation on its own can never establish.
- Correlation coefficientA correlation coefficient is a number between −1 and 1 saying how closely the points on a scatter graph lie to a straight line, and in which direction.
- CounterexampleA single example that satisfies a statement's conditions but not its conclusion, which is enough to prove the statement false.
- Cube rootThe cube root of a number is the value that gives that number when multiplied by itself three times; ∛64 = 4 because 4 × 4 × 4 = 64.
D
- Dangling modifierA dangling modifier is a descriptive phrase whose implied subject does not appear as the subject of the clause it is attached to.
- DenominatorThe denominator is the number below the line in a fraction, stating how many equal parts the whole has been divided into.
- DeterminerA determiner is a word placed in front of a noun to specify which one, whose, or how many are meant, such as the, this, my or several.
- Difference of two squaresAn expression made by subtracting one square from another, of the form a² − b², which always factorises into (a + b)(a − b).
- DiffusionDiffusion is the spreading out of particles from where they are crowded to where they are not, until they are evenly mixed.
- Discrete and continuous dataDiscrete data can only take separate fixed values that you count, while continuous data comes from measuring and can take any value within a range.
- DiscriminantThe part of the quadratic formula under the square root, b² − 4ac, whose sign tells you whether a quadratic has two real roots, one, or none.
- DistillationDistillation is a separation method in which a mixture is boiled and the vapour given off is cooled back into a liquid and collected apart from the rest.
- Domain of a functionThe set of input values a function is allowed to take — every x for which the rule produces a real answer.
- Dominant and recessive allelesA dominant allele shows its effect whenever it is present; a recessive allele shows only when both of an organism's alleles are recessive.
E
- Equilateral triangleAn equilateral triangle has three sides of equal length and three equal interior angles, each of which measures exactly 60 degrees.
- Error intervalAn error interval is the range of values a rounded or truncated measurement could have come from, written as an inequality between its lower and upper bounds.
- Exam boardAn exam board, or awarding body, is the organisation that publishes a specification, sets and marks the exam papers and issues the grade for a qualification.
- Exam seriesAn exam series is one scheduled window in which a board runs its papers, carrying a single timetable, one set of grade boundaries and one results day.
- Exothermic and endothermic reactionsAn exothermic reaction gives out energy and warms its surroundings; an endothermic reaction takes energy in and cools them.
- Expected frequencyExpected frequency is the number of times an outcome should occur on average, found by multiplying its probability by the number of trials.
- Exponential functionA function in which the variable appears as the power, written y = ka^x, so y is multiplied by the same factor each time x increases by one.
- ExtrapolationExtrapolation is estimating a value by continuing a pattern beyond the range of the data that was actually collected, which makes the estimate unreliable.
F
- ForeshadowingForeshadowing is a detail placed early in a story that hints at something happening later, so that the later event feels prepared for rather than sudden.
- FrequencyFrequency is the number of complete waves passing a fixed point each second, measured in hertz, where one hertz means one wave per second.
- Frequency densityFrequency density is the frequency of a class divided by its width, and it is the quantity plotted up the vertical axis of a histogram.
- Fronted adverbialA fronted adverbial is an adverbial moved from its usual position to the start of a sentence, where it is normally followed by a comma.
- FunctionA rule that assigns exactly one output to each input it accepts, so no input is ever sent to two different values.
G
- GenotypeA genotype is the pair of alleles an organism carries for a particular gene, usually written as two letters such as BB, Bb or bb.
- Geometric sequenceA sequence in which each term is found by multiplying the previous one by the same fixed number, called the common ratio.
- Grade boundaryA grade boundary is the lowest raw mark that earns a particular grade, fixed after marking so that the same grade represents the same standard across series.
- GradientA measure of how steep a line is, found by dividing the change in y by the change in x between any two points on it.
- Grading on a curveGrading on a curve means grades are set by how candidates rank against each other rather than against a fixed mark, so the same performance can earn different grades.
H
- HomeostasisHomeostasis is the way the body holds its internal conditions steady, such as temperature and blood glucose, while conditions outside it change.
- HyperboleHyperbole is deliberate exaggeration used for effect, stated as though it were literal but intended to be recognised as an overstatement.
- HypotenuseThe longest side of a right-angled triangle, the one lying directly opposite the right angle.
I
- Improper fractionAn improper fraction is one whose numerator is greater than or equal to its denominator, so its value is 1 or more — for example 7/4.
- Independent eventsTwo events are independent when the outcome of one has no effect on the probability of the other, so the probability of both equals the two probabilities multiplied.
- InferenceAn inference is a conclusion a reader reaches from evidence in a text about something the writer has implied but not stated directly.
- IntegerAn integer is any number in the list …, −3, −2, −1, 0, 1, 2, 3, … — a whole number, positive, negative or zero, with no fractional part.
- Interquartile rangeThe interquartile range is the upper quartile minus the lower quartile: the width of the middle half of an ordered data set.
- Inverse functionThe function that reverses another, sending each output of f back to the input it came from, and written f⁻¹.
- IonAn ion is an atom or group of atoms that has lost or gained electrons and therefore carries a positive or negative electrical charge.
- IronyIrony is a gap between appearance and reality: between what a speaker says and means, what is expected and what happens, or what a character knows and the audience knows.
- Irrational numberAn irrational number is a real number that cannot be written as a fraction of two integers, so its decimal runs on for ever without ever repeating.
- Isosceles triangleAn isosceles triangle has two sides of equal length, and the two angles opposite those equal sides are also equal to each other.
- IsotopeIsotopes are atoms of the same element with the same number of protons but different numbers of neutrons, and therefore different mass numbers.
K
L
- Like termsLike terms are terms whose letter parts are identical, including the powers, so they can be added or subtracted into one term.
- Linear equationAn equation in which every variable appears only to the power one, with no variables multiplied together, so its graph is a straight line.
- Linear qualificationA linear qualification is assessed entirely at the end of the course in one exam series, rather than in units taken and banked while the course is still running.
- LocusThe set of all points that satisfy a given rule about distance or position, drawn as the path or region those points form.
M
- Margin of errorThe margin of error is the amount added to and subtracted from a survey result to give the range in which the true population value plausibly lies.
- MeanderA meander is a bend in a river channel, maintained by erosion on the faster-flowing outer bank and deposition on the slower-flowing inner bank.
- MeiosisMeiosis is the cell division that makes gametes, dividing one cell twice to produce four genetically different cells with half the chromosome number.
- MetaphorA metaphor describes one thing as if it were another, transferring a quality from the second to the first without using like or as.
- MidpointThe midpoint of a line segment is the point exactly halfway between its two endpoints, found by averaging their x-coordinates and their y-coordinates.
- MitosisMitosis is the division of a cell nucleus that produces two daughter cells with identical DNA and the same chromosome number as the original.
- Mixed numberA mixed number is a whole number written next to a proper fraction, meaning the two added together — 2 3/4 means 2 + 3/4.
- Modal classThe modal class is the group in a grouped frequency table that contains more values than any other group.
- Modal verbA modal verb is a helping verb such as must, should or might that shows how certain, possible, permitted or obligatory the main verb's action is.
- ModerationModeration is an exam board's check on a school's marking of internally assessed work, shifting that school's whole cohort up or down if the marking proves too generous or severe.
- Mutually exclusive eventsTwo events are mutually exclusive if they cannot both happen at the same time, so on any single trial at most one of them occurs.
N
- Natural numberA natural number is one of the counting numbers — 1, 2, 3, 4 and onwards — though some conventions, including the standard ISO 80000-2, begin the list at 0.
- NetA net is a flat arrangement of a solid's faces, joined at their edges, that folds along those edges to form the solid without gaps or overlaps.
- NumeratorThe numerator is the number written on top of a fraction, and it counts how many of the equal parts are being taken.
O
- OnomatopoeiaOnomatopoeia is a word that imitates the sound it refers to, so that saying the word produces something close to the noise itself.
- OsmosisOsmosis is the net movement of water across a partially permeable membrane, from a dilute solution to a more concentrated one.
- OutlierAn outlier is a data value that lies far enough away from the rest of the data set to stand apart from it.
P
- Parallel linesLines in the same plane that stay the same distance apart for ever and so never meet, however far they are extended.
- Parallel structureParallel structure is the rule that words or phrases joined by and, or, or a paired conjunction must arrive in the same grammatical form as one another.
- ParallelogramA parallelogram is a quadrilateral with two pairs of parallel sides, which forces its opposite sides and opposite angles to be equal.
- Percentage multiplierA percentage multiplier is the single number an amount is multiplied by to apply a percentage change, such as 1.15 for a 15% increase.
- Percentage pointA percentage point is the difference between two percentages found by subtracting one from the other, as distinct from the percentage change between them.
- Percentile rankA percentile rank is the percentage of test takers in a stated comparison group who scored at or below a given score.
- PerpendicularTwo lines are perpendicular when they meet or cross at a right angle, exactly 90°.
- Perpendicular bisectorThe line that crosses a line segment at its midpoint at 90°, made up of every point that is the same distance from the segment's two ends.
- PersonificationPersonification describes a non-human thing as though it had human qualities or performed human actions, such as a wind that howls or a house that groans.
- PhenotypeA phenotype is the characteristic an organism actually shows, produced by its alleles together with the conditions it has grown in.
- PhonemeA phoneme is the smallest unit of sound in a spoken word: change one phoneme and the word changes, as pin becomes bin.
- Pi (π)Pi is the ratio of a circle's circumference to its diameter — approximately 3.14159, and identical for every circle regardless of size.
- Plan and elevationA plan is the view of a solid from directly above; an elevation is the view from directly in front of it or directly from one side.
- PolygonA closed two-dimensional shape made only of straight sides, each side meeting two others end to end.
- PolymerA polymer is a large molecule formed when many small molecules, called monomers, join together into a long repeating chain.
- Population and sampleThe population is every member of the group being studied; a sample is the smaller part of that group which is actually measured.
- Potential differencePotential difference is the energy transferred per coulomb of charge as it moves between two points in a circuit, measured in volts.
- Predicted gradeA predicted grade is a school's judgement, made before the exams, of the grade it expects a student to achieve — produced by teachers, never by the exam board.
- PressurePressure is the force acting at right angles to a surface divided by the area over which that force is spread, measured in pascals.
- Primary sourceA primary source is evidence created at the time of the event being studied, by someone who took part in it or witnessed it directly.
- PrismA prism is a solid whose cross-section is the same shape and size all the way along its length, with two identical parallel end faces.
- PropagandaPropaganda is information presented in a deliberately one-sided way in order to persuade an audience to hold a particular view or take a particular action.
- ProtagonistThe protagonist is the character whose goal drives the plot and around whose choices the story is organised, whether or not the reader is meant to approve.
- Pythagorean tripleA Pythagorean triple is a set of three positive whole numbers a, b and c for which a² + b² = c², so they form a right-angled triangle.
Q
- Quadratic sequenceA sequence whose second differences are all the same non-zero number, which means its nth term rule contains an n² term.
- QuadrilateralA quadrilateral is a flat shape with four straight sides and four corners, whose interior angles always add up to 360 degrees.
- Qualitative and quantitative dataQualitative data describes a quality in words or categories, while quantitative data records a quantity as a number that has been counted or measured.
- QuartileA quartile is one of the three values that split an ordered data set into four equally sized parts.
- QuotientThe quotient is the result of a division — the number of times the divisor goes into the dividend.
R
- RadianA radian is the angle at the centre of a circle that cuts off an arc equal in length to the radius.
- Random sampleA random sample is one chosen so that every member of the population has an equal chance of being selected.
- Range of a functionThe set of output values a function actually produces once every input in its domain has been used.
- Rational numberA rational number is any number that can be written as a fraction a/b where a and b are integers and b is not zero.
- ReciprocalThe reciprocal of a number is 1 divided by it — the number you multiply by to reach 1, found by turning a fraction upside down.
- Recurring decimalA recurring decimal is a decimal in which one digit or a block of digits repeats without end, shown by placing a dot over the repeating part.
- Reflex angleAn angle bigger than 180° but smaller than 360°: more than a straight line, less than a complete turn.
- RefractionRefraction is the bending of a wave as it passes from one material into another, caused by the change in the wave's speed at the boundary.
- Relative atomic massRelative atomic mass is the mean mass of an element's atoms, weighted by isotope abundance, compared with one twelfth of the mass of a carbon-12 atom.
- Relative clauseA relative clause is a subordinate clause that describes a noun, usually introduced by a relative pronoun such as who, which, that or whose.
- Relative frequencyRelative frequency is the number of times an outcome occurred divided by the total number of trials, used as an estimate of that outcome's probability.
- RemainderA remainder is the amount left over when one whole number does not divide exactly into another, and it is always smaller than the divisor.
- RhombusA rhombus is a quadrilateral with four sides of equal length whose opposite sides are parallel and whose diagonals cross at right angles.
- Rhyme schemeA rhyme scheme is the pattern made by the rhyming words at the ends of lines, recorded by giving each new rhyme sound the next letter of the alphabet.
- Roots of an equationThe values of the variable that make an equation true; for an equation written as f(x) = 0 they are exactly where the graph of f meets the x-axis.
S
- Sample spaceA sample space is the complete list of every possible outcome of an experiment, with each outcome written down exactly once.
- Sampling biasSampling bias is the error that arises when the way a sample is chosen makes some members of the population more likely to be included than others.
- Scalar and vector quantitiesA scalar is a quantity with magnitude only; a vector is a quantity that has both a magnitude and a direction, such as force or velocity.
- Scale factorA scale factor is the number by which every length in a shape is multiplied to produce an enlarged or reduced copy of the same shape.
- Scaled scoreA scaled score is a raw mark converted onto a fixed reporting scale, so that the same score means the same level of attainment whichever version was sat.
- SectorA sector is the region of a circle enclosed by two radii and the arc between their endpoints, like a slice cut from a whole pizza.
- SegmentA segment is the region of a circle cut off by a chord, lying between that chord and one of the two arcs the chord separates.
- SemicolonA semicolon is a punctuation mark that joins two closely related independent clauses, or separates list items that already contain commas.
- Significant figuresSignificant figures are the digits in a number that carry information about its size, counted from the first non-zero digit onwards.
- SimileA simile is a comparison between two unlike things, made openly with the word like or as, in order to give one of them a quality of the other.
- Simplest formA fraction is in simplest form when its numerator and denominator have no common factor other than 1, so no further cancelling is possible.
- Skewed distributionA skewed distribution is one whose graph is not symmetrical, having a longer tail stretching out on one side than on the other.
- Solute and solventA solute is a substance that dissolves in a liquid, the solvent is the liquid that dissolves it, and the mixture they form together is a solution.
- Specification codeA specification code is a short alphanumeric reference identifying one exact version of one qualification from one exam board, such as 1MA1 or 0580.
- Square numberA square number is what you get by multiplying an integer by itself, giving 1, 4, 9, 16, 25 and so on.
- Square rootA square root of a number is a value that gives that number when multiplied by itself; the sign √ denotes the positive one, so √25 = 5.
- Standard deviationStandard deviation is a measure of spread: roughly, how far a typical value sits from the mean of its data set.
- Stem-and-leaf diagramA stem-and-leaf diagram displays data in order by splitting each value into a stem, usually the leading digits, and a leaf, usually the final digit.
- StomataStomata are tiny pores in the surface of a leaf, mostly on the underside, that open and close to let gases in and out.
- Stratified sampleA stratified sample splits the population into groups and takes from each group a number of members in proportion to that group's size.
- Subject of a formulaThe subject of a formula is the single letter that stands alone on one side of the equals sign, with every other letter on the other side.
- Subordinate clauseA subordinate clause contains a subject and a verb but cannot form a sentence by itself; it depends on a main clause to complete its meaning.
- SurdA surd is a root of a rational number that is itself irrational, so it cannot be written exactly and is left in root form.
- Surface areaSurface area is the total area of all the faces and curved surfaces of a solid added together, measured in square units such as cm².
- SyllableA syllable is one beat of a spoken word, containing exactly one vowel sound, with or without consonants around it.
- SyntaxSyntax is the set of rules and choices governing how words are ordered and combined into phrases, clauses and sentences.
T
- Terminal velocityTerminal velocity is the constant speed reached by a falling object once the upward drag force acting on it has become equal in size to its downward weight.
- TessellationA tiling of a flat surface by shapes that fit together with no gaps and no overlaps, and which could continue for ever in every direction.
- Test-optionalTest-optional means a university considers an SAT or ACT score only if the applicant chooses to submit one, and does not penalise an application that arrives without one.
- The distributive propertyThe distributive property states that multiplying a sum gives the same result as multiplying each part separately and adding, so a(b + c) = ab + ac.
- Thesis statementA thesis statement is a single sentence stating the arguable claim an essay sets out to prove, placed early so a reader knows what is being argued.
- TieringTiering is the practice of examining one GCSE subject through two separate sets of papers, Foundation and Higher, each able to award only part of the grade range.
- Topic sentenceA topic sentence states the single point a paragraph will make, so that every sentence after it can be read as support for that point.
- TrapeziumA trapezium is a quadrilateral with one pair of parallel sides; the remaining two sides need be neither parallel, equal, nor at any particular angle.
- Triangular numberA triangular number is the total you get by adding the whole numbers from 1 up to some point, so that many dots can be arranged in an equal-sided triangle.
- Turning pointA point where a graph stops rising and begins to fall, or stops falling and begins to rise.
- Two-way tableA two-way table sorts one group of people or things by two different categories at once, showing how many fall into each combination.
U
V
W
- WavelengthWavelength is the distance between one point on a wave and the identical point on the next wave, such as from one crest to the next crest.
- WeatheringWeathering is the breaking down of rock in the place where it lies, by physical, chemical or biological processes, without the fragments being carried away.
X
Y
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