Mathematics · Year 9
48 interactive lessons to explore
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📚 Term 1 · Lessons 1–12
›Lesson 1
The real number system
Sort numbers into natural numbers, integers, rationals and irrationals, and see how these sets fit together inside the real numbers.
⏱ 18 min · 10 questions
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Lesson 2
Approximating irrational numbers
Trap square roots and cube roots between known values, refine the estimate to one decimal place and check it with a calculator.
⏱ 18 min · 10 questions
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Lesson 3
Significant figures
Count and round to significant figures, and choose a sensible level of accuracy for answers calculated from real measurements.
⏱ 18 min · 10 questions
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Lesson 4
Negative indices
Extend the index laws to negative exponents, write a⁻ⁿ as 1/aⁿ and evaluate numerical expressions with negative powers.
⏱ 18 min · 11 questions
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Lesson 5
Index laws with variables
Combine every index law, including zero and negative indices, to simplify algebraic expressions with coefficients and several pronumerals.
⏱ 20 min · 11 questions
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Lesson 6
Scientific notation
Write very large and very small numbers in scientific notation and convert them back to ordinary decimal form.
⏱ 18 min · 11 questions
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Lesson 7
Calculating in scientific notation
Multiply and divide numbers in scientific notation using the index laws and a calculator, then tidy the answer into correct form.
⏱ 20 min · 11 questions
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Lesson 8
Very large and small measurements
Use metric prefixes and scientific notation to solve problems about cells, viruses, planets and stars.
⏱ 20 min · 11 questions
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Lesson 9
Absolute error and limits of accuracy
Recognise that every measurement is an estimate, and find the absolute error and the upper and lower limits of a measurement.
⏱ 18 min · 11 questions
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Lesson 10
Relative and percentage error
Calculate relative and percentage errors and use them to decide which of two measurements is more accurate.
⏱ 18 min · 11 questions
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Lesson 11
Simple interest
Use the formula I = Prn to calculate simple interest earned on savings or charged on loans, including periods given in months or days.
⏱ 18 min · 10 questions
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Lesson 12
Simple interest problems
Rearrange I = Prn to find the principal, rate or time, and compare simple interest loans and savings options to make good decisions.
⏱ 20 min · 12 questions
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📚 Term 2 · Lessons 13–24
›Lesson 13
Expanding binomial products
Multiply two binomials such as (x + 3)(x − 5) term by term, then collect like terms to simplify the result.
⏱ 18 min · 10 questions
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Lesson 14
Special binomial products
Recognise and expand perfect squares and differences of two squares using their patterns, and use them for quick mental arithmetic.
⏱ 18 min · 10 questions
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Lesson 15
Factorising monic quadratics
Reverse binomial expansion by finding two numbers with a given sum and product to factorise quadratics like x² + 7x + 12.
⏱ 20 min · 10 questions
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Lesson 16
Factorising a difference of squares
Factorise differences of two squares and perfect squares, and choose the right factorising method for any quadratic expression.
⏱ 20 min · 10 questions
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Lesson 17
Gradient of a line
Measure the steepness of a line segment with rise over run and the gradient formula, and interpret positive, negative, zero and undefined gradients.
⏱ 18 min · 10 questions
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Lesson 18
Midpoint of an interval
Find the midpoint of a line interval by averaging coordinates, and work backwards to find a missing endpoint.
⏱ 16 min · 10 questions
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Lesson 19
Distance between two points
Use Pythagoras’ theorem and the distance formula to find exact and rounded distances between points on the Cartesian plane.
⏱ 18 min · 10 questions
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Lesson 20
Gradient–intercept form
Read the gradient and y-intercept straight from y = mx + c and sketch lines quickly without a table of values.
⏱ 18 min · 11 questions
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Lesson 21
Finding the equation of a line
Work out the equation of a straight line from its graph, from a point and the gradient, or from two points.
⏱ 20 min · 11 questions
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Lesson 22
Changing parameters of lines
Explore with a graphing tool how changing m and c moves and turns a line, and use equal gradients to find parallel lines.
⏱ 18 min · 10 questions
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Lesson 23
Graphing simple parabolas
Plot y = x², y = ax² and y = x² + k, and describe how changing a and k changes the width, direction and position of a parabola.
⏱ 20 min · 10 questions
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Lesson 24
Linear, quadratic and exponential change
Tell linear, quadratic and exponential patterns apart using differences and ratios, and choose the right model for a real situation.
⏱ 20 min · 10 questions
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📚 Term 3 · Lessons 25–36
›Lesson 25
Surface area of prisms
Unfold triangular, trapezoidal and composite right prisms into nets and add the areas of every face to find the total surface area.
⏱ 18 min · 11 questions
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Lesson 26
Surface area of cylinders
Derive the surface area formula for a cylinder from its net and apply it to closed and open cylinders such as cans, pipes and water tanks.
⏱ 18 min · 10 questions
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Lesson 27
Volume of cylinders
Use V = πr²h to find the volume and capacity of cylinders, and rearrange it to find an unknown radius or height.
⏱ 18 min · 10 questions
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Lesson 28
Enlargements and scale factors
Enlarge and reduce shapes by a scale factor, identify what changes and what stays the same, and use scale factors to find unknown lengths.
⏱ 17 min · 11 questions
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Lesson 29
Similar figures
Use enlargement to explain similarity, match corresponding sides and angles, and find unknown lengths in similar figures.
⏱ 18 min · 10 questions
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Lesson 30
Conditions for similar triangles
Apply the AAA, SSS, SAS and RHS tests to show two triangles are similar, then use them to solve problems such as finding heights from shadows.
⏱ 19 min · 10 questions
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Lesson 31
Algorithms for constructions
Follow, test and refine step-by-step compass-and-ruler algorithms for bisecting angles and intervals and constructing perpendiculars.
⏱ 18 min · 10 questions
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Lesson 32
Trigonometric ratios
Label the opposite, adjacent and hypotenuse sides of a right-angled triangle and use similar triangles to explain why sine, cosine and tangent are fixed for each angle.
⏱ 18 min · 10 questions
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Lesson 33
Finding sides with trigonometry
Choose sine, cosine or tangent and use a calculator to find an unknown side length in a right-angled triangle.
⏱ 19 min · 11 questions
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Lesson 34
Finding angles with trigonometry
Use inverse sine, cosine and tangent on a calculator to find an unknown angle in a right-angled triangle from two known sides.
⏱ 18 min · 11 questions
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Lesson 35
Angles of elevation and depression
Draw clear diagrams for worded problems involving angles of elevation and depression, then solve them using trigonometry.
⏱ 19 min · 11 questions
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Lesson 36
Bearings and direction
Read and write true and compass bearings, and solve navigation problems using Pythagoras’ theorem and trigonometry.
⏱ 20 min · 11 questions
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📚 Term 4 · Lessons 37–48
›Lesson 37
Evaluating statistics in the media
Question the surveys, graphs and numbers in news stories and ads to spot misleading claims, weak samples and conclusions the data cannot support.
⏱ 18 min · 10 questions
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Lesson 38
Histograms and grouped data
Group numerical data into class intervals, draw and read frequency histograms and polygons, and estimate the mean from grouped data.
⏱ 20 min · 10 questions
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Lesson 39
Back-to-back stem-and-leaf plots
Read and build back-to-back stem-and-leaf plots, then use them to compare the centre and spread of two data sets.
⏱ 18 min · 10 questions
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Lesson 40
Comparing distributions
Describe the shape of a distribution and compare data sets using the mean, median and range, choosing the most suitable measure of centre.
⏱ 18 min · 10 questions
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Lesson 41
Choosing data displays
Classify data by type, choose and justify a suitable display, and calculate and interpret sector angles in pie charts.
⏱ 18 min · 10 questions
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Lesson 42
Bivariate data and bias
Identify bivariate numerical data, plan an investigation into two related variables and recognise sources of bias that could distort the results.
⏱ 18 min · 10 questions
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Lesson 43
Two-step compound events
List every outcome of a two-step experiment using arrays, tables and tree diagrams, and calculate probabilities of compound events.
⏱ 20 min · 10 questions
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Lesson 44
With and without replacement
Compare two-step probabilities with and without replacement, adjusting the second-stage branches of a tree diagram when items are not returned.
⏱ 20 min · 9 questions
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Lesson 45
'And' and 'or' events
Use Venn diagrams and two-way tables to find the probability of ‘and’, inclusive ‘or’ and exclusive ‘or’ events.
⏱ 20 min · 10 questions
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Lesson 46
Estimating with relative frequency
Calculate relative frequencies from recorded data to estimate the probability of compound events and predict expected frequencies.
⏱ 18 min · 10 questions
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Lesson 47
Simulating compound events
Design spreadsheet simulations of two-step events and compare the probability of a simple event with related ‘both’ and ‘at least one’ events.
⏱ 20 min · 10 questions
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Lesson 48
Data and chance in context
Work through a complete statistical investigation, choosing displays, calculating summary statistics and judging bias to answer a real-world question.
⏱ 20 min · 10 questions