Lesson library

Every solution is a clear written walkthrough paired with a concise video. Browse by grade and topic below.

Thumbnail showing KJSEA 2025 Maths Question 26 on simultaneous equations for books and pens with worked elimination steps.
Grade 9 • Algebra

KJSEA 2025 Maths Q26 — Simultaneous Equations

Solve two simultaneous equations by elimination to find the cost of a book and a pen.

Number cards 2, 4, 5 and 9 with a question asking which set holds prime numbers only.
Grade 9 • Numbers

KJSEA 2025 Maths Q1: Prime Numbers

Which set has prime numbers only? Test 2, 4, 5 and 9 with the two-factor rule.

Thumbnail showing a cylindrical bucket of water with the surface area of a cylinder formula for KJSEA 2025 Maths Question 10.
Grade 9 • Measurement

KJSEA 2025 Maths Q10 — Cylinder Surface Area

Find the bucket surface touching the water: circular base plus curved wall, top left out.

Thumbnail showing a cuboid milk packet with dimensions and the KJSEA 2025 Maths Q11 capacity question
Grade 9 • Measurement

KJSEA 2025 Q11 — Capacity

Find the capacity of a cuboid milk packet in litres.

Video thumbnail showing the Kelvin to Celsius conversion for KJSEA 2025 Maths Question 12.
Grade 9 • Measurement

KJSEA 2025 Q12 — Kelvin to Celsius

Choose the calculation that converts a Kelvin reading to degrees Celsius.

Video thumbnail showing a mobile money charges table with the question about how much Loymer remained with after sending and withdrawing money.
Grade 9 • Numbers

Q13 — Mobile Money Charges

Work out the balance left after sending and withdrawing money plus charges.

Thumbnail showing a window with an estimated height of 1.5 m and an actual height of 1.2 m, with the percentage error calculation 0.3 over 1.2 times 100.
Grade 9 • Measurement

KJSEA 2025 Maths Q14 — Percentage Error

Which calculation gives the percentage error when an estimate of 1.5 m misses the actual 1.2 m?

Video thumbnail showing a rhombus with its diagonals crossing at right angles, labelled KJSEA 2025 Maths Question 15.
Grade 9 • Geometry

KJSEA 2025 Maths Q15 — Quadrilaterals

Which quadrilateral has diagonals that bisect each other at 90 degrees? It's the rhombus.

Video thumbnail showing an architectural wall drawing with the scale 1 to 100 and Q16 Scale Drawing title.
Grade 9 • Measurement

Q16 Scale Drawing

Use a 1:100 scale to find how long a 3 m wall is on the drawing.

Thumbnail showing the line equation 2y = x + 3 with the question 'gradient of the perpendicular line L2?' for KJSEA 2025 Maths Q17.
Grade 9 • Geometry

KJSEA 2025 Maths Q17 — Perpendicular Gradient

Find the gradient of a line perpendicular to 2y = x + 3 using the negative reciprocal rule.

Thumbnail showing an original 16 cm photograph and its enlarged copy that is twice as long, with the enlargement calculation.
Grade 9 • Geometry

KJSEA 2025 Q18 — Enlargement

Enlarge a 16 cm photograph by a scale factor of 2 to find its new length.

Thumbnail showing KJSEA 2025 Grade 9 Maths Question 2 on finding the HCF of 120, 180 and 24
Grade 9 • Numbers

KJSEA 2025 Maths Q2 — HCF

Find the largest number of equal groups by taking the HCF of 120, 180 and 24.

Thumbnail showing 11 lettered cards with the three E cards highlighted and the fraction 3/11 for KJSEA 2025 Maths Question 20.
Grade 9 • Statistics

KJSEA 2025 Maths Q20 — Probability

Find the probability of drawing a card marked E from 11 lettered cards.

Thumbnail showing KJSEA 2025 Grade 9 Maths Question 21 on place value and rounding a distance in a 10,000 metre race.
Grade 9 • Numbers

KJSEA 2025 Maths Q21 — Place Value & Rounding

Subtraction, number words and rounding 6,784 to the nearest 100.

Thumbnail showing a large metallic cube container with the question 'How many small cubes fit inside?' and KJSEA 2025 Maths Q22.
Grade 9 • Measurement

KJSEA 2025 Maths Q22 — Volume & Packing

Find a cube's volume, then count how many small cubes fit inside.

Video thumbnail showing KJSEA 2025 Grade 9 Maths Question 23 on ratio, with the ratio 5:7:3 and 60 children.
Grade 9 • Numbers

KJSEA 2025 Maths Q23 — Ratio

Sharing a Thanksgiving crowd in the ratio 5:7:3 to find men, women, and the difference.

Video thumbnail showing a KJSEA 2025 Grade 9 Maths work-rate question about men, hours and days packing flour.
Grade 9 • Numbers

KJSEA 2025 Maths Q24 — Work Rate

Solve a work-rate problem using man-hours to find how many extra days are needed.

Video thumbnail showing the recurring decimal 0.17 being converted step by step into the fraction 8 over 45.
Grade 9 • Numbers

Q25 — Recurring Decimal to Fraction

Turn 0.17 recurring into a fraction using the multiply-and-subtract trick.

Video thumbnail showing KJSEA 2025 Grade 9 Maths Question 27 on matrices, with two 2 by 3 fruit-purchase matrices being added.
Grade 9 • Algebra

KJSEA 2025 Maths Q27 — Matrices

Form two 2 by 3 matrices for weekly fruit buys, then add them to get each family's totals.

Thumbnail showing a straight line on a coordinate grid passing through the point (1, 4) with its equation and x-intercept.
Grade 9 • Geometry

Q28 — Equation of a Line

Point-gradient form to find a line through (1, 4), then solve for the x-intercept.

Diagram of a solid cone with slant height 20 cm and base radius 4.2 cm, titled KJSEA 2025 Maths Q29.
Grade 9 • Measurement

KJSEA 2025 Maths Q29 — Surface Area of a Cone

Find the total surface area of a solid cone with slant height 20 cm and radius 4.2 cm.

Video thumbnail showing a number line with an arrow moving from -8 to +7 for a KJSEA 2025 integers question.
Grade 9 • Numbers

KJSEA 2025 Maths Q3 — Integers

Add a positive integer to a negative one to find a new temperature.

Thumbnail showing a cylindrical tin of water with a spherical ball being lowered in, and the label Q30 Volume and Displacement.
Grade 9 • Measurement

KJSEA 2025 Maths Q30 — Volume & Displacement

A ball sinks in a tin — find how much the water rises using displacement.

Thumbnail showing a metal rod leaning against a wall forming a right-angled triangle, with Pythagoras and density formulas.
Grade 9 • Measurement

KJSEA 2025 Maths Q31: Pythagoras & Density

Find a leaning rod's length with Pythagoras, then work out density from mass and volume.

Video thumbnail showing a globe with longitude lines and clocks marking the time at towns P and Q for KJSEA 2025 Maths Q32.
Grade 9 • Measurement

KJSEA 2025 Q32 — Longitude & Time

Use the longitude difference between two towns to work out the local time at town P.

Video thumbnail showing KJSEA 2025 Grade 9 Maths Question 33 on import duty, excise duty and VAT for an imported printing machine.
Grade 9 • Numbers

KJSEA 2025 Q33 — Import Duty, Excise & VAT

Work out import duty, excise duty and VAT as percentages of a Ksh 1.2 million customs value.

Ruler-and-compasses construction of parallelogram ABCD with a 45 degree angle at A and a perpendicular dropped from D to AB at E.
Grade 9 • Geometry

KJSEA 2025 Maths Q34 — Parallelogram Construction

Construct parallelogram ABCD, drop a perpendicular from D to AB, and measure DE.

Thumbnail showing a linear graph rising from the origin with the equation y = 50x for milk sales
Grade 9 • Algebra

Q35 — Linear Graphs

Complete the table for y = 50x and draw the milk-earnings line.

Diagram of a building with a person on a balcony looking down at a ball 47 m away, showing a 35 degree angle of depression
Grade 9 • Trigonometry

KJSEA 2025 Maths Q36 — Angle of Depression

Find the height of Dowdy's balcony using a 35° angle of depression and the tangent ratio.

Scale drawing showing a route from A to B to C with north lines and bearings, and the line AC measured for distance and bearing
Grade 9 • Geometry

KJSEA 2025 Maths Q37 — Bearings

Draw the two legs to scale, join A to C, then measure to get 86 m on a bearing of 174°.

Thumbnail showing a cuboid unfolded into a flat net with the label Q38 Net and Surface Area, KJSEA 2025 Grade 9 Maths.
Grade 9 • Measurement

KJSEA 2025 Q38 — Cuboid Net & Surface Area

Draw the net of a 5 by 3 by 2 cm cuboid and add all six faces to get 62 cm squared.

Video thumbnail showing KJSEA 2025 Grade 9 Maths Question 39 on statistics, with a frequency table and the mean and median calculations.
Grade 9 • Statistics

KJSEA 2025 Maths Q39 — Mean & Median

Tally 20 test marks into a frequency table, then calculate the mean and median.

Video thumbnail showing KJSEA 2025 Grade 9 Maths Question 4 on fractions of time, with the calculation for extra time planting seedlings.
Grade 9 • Numbers

KJSEA 2025 Maths Q4 — Fractions of Time

Which calculation gives the extra time used planting 70 seedlings? A clear fractions-of-time walkthrough.

Thumbnail showing a coin and a die with a grid of all possible outcomes for KJSEA 2025 Maths Question 40.
Grade 9 • Statistics

KJSEA 2025 Maths Q40 — Probability Space

List all 12 outcomes of tossing a coin and a die, then find the probability of a head and a four.

Thumbnail showing a flash card with the index equation 2 to the power X times 2 cubed equals 32, labelled KJSEA 2025 Maths Q5 Indices.
Grade 9 • Numbers

KJSEA 2025 Maths Q5 — Indices

Use the laws of indices to solve 2^X × 2^3 = 32 and find X.

Thumbnail showing KJSEA 2025 Grade 9 Maths Question 6 on algebraic expressions, with a farm animals word problem.
Grade 9 • Algebra

KJSEA 2025 Q6 — Algebraic Expressions

Write an algebraic expression for the number of sheep on a 26-animal farm.

Number line for KJSEA 2025 Maths Q7 with a solid dot at 30 and an open circle at 50
Grade 9 • Algebra

KJSEA 2025 Maths Q7 — Inequalities

Turn 'at least 30 but fewer than 50 learners' into a compound inequality and graph it.

Video thumbnail showing a football results matrix with the question asking for the order of the matrix.
Grade 9 • Algebra

KJSEA 2025 Maths Q8 — Order of a Matrix

Count the rows and columns to state a matrix's order — worked step by step.

Thumbnail showing the algebraic fraction (x squared minus 4y squared) over (x squared plus 4xy plus 4y squared) being simplified.
Form 4 • Algebra

KCSE 2025 P1 Q7 — Algebraic Fractions

Factorise the top and bottom, cancel the common factor, and simplify the algebraic fraction.

Thumbnail showing a square-root surd expression being evaluated step by step for KCSE 2025 Maths Paper 1 Question 1.
Form 4 • Numbers

KCSE 2025 Maths P1 Q1 — Order of Operations

Use BODMAS and fraction skills to evaluate a square-root expression by hand.

Video thumbnail showing a thin square brass plate with the density, mass and volume formula for finding its side length.
Form 3 • Measurement

Density: Length of a Brass Plate

Use density, mass and thickness to find the side length of a thin square brass plate.

Video thumbnail showing a BODMAS fraction expression being evaluated step by step, with the word BODMAS highlighted.
Form 3 • Numbers

Form 3 P1 Q1 — BODMAS Evaluation

Use BODMAS to evaluate a signed-number fraction and get -2.

Video thumbnail showing two algebraic fractions being added and simplified on a whiteboard for Alliance Form 3 Paper 1 Question 11.
Form 3 • Algebra

Alliance F3 P1 Q11 — Algebraic Fractions

Add two algebraic fractions and simplify by finding the common denominator.

Video thumbnail showing a slow clock time problem for Alliance Form 3 Paper 1 Question 12
Form 3 • Measurement

Q12 Time — A Slow Clock

A clock loses 15 seconds every hour — find what it shows after 60 hours.

Thumbnail showing a cube with one square face highlighted and its corner-to-corner diagonal drawn in
Form 3 • Measurement

Diagonal of a Cube Face

Use the volume to find the edge, then Pythagoras for the face diagonal.

Video thumbnail showing a compound linear inequality being solved and graphed on a number line.
Form 3 • Algebra

Form 3 P1 Q14 — Linear Inequalities

Split a compound inequality into two parts, solve each, and graph the solution on a number line.

Thumbnail showing position vectors OA and OB plotted on a grid with the arrow AB and the label Q15 Vectors Magnitude.
Form 3 • Geometry

Vectors: Magnitude of AB

Find AB from OA and OB, then use Pythagoras to get its length to one decimal place.

Video thumbnail showing Alliance Form 3 Paper 1 Question 17 on ratio and profit, featuring a farmer's maize bags and lorry transport.
Form 3 • Numbers

Ratio, Trips & Profit — Q17

A three-part ratio and profit problem: mass lost after drying, number of lorry trips, and the selling price for a 26% profit.

Video thumbnail showing a rectangular floor being covered with square tiles and a shilling cost calculation for Alliance Form 3 Paper 1 Question 18.
Form 3 • Measurement

Alliance F3 P1 Q18 — Tiles & Profit

Count the tiles for a floor, cost 15 rooms, then price each carton for a 12.5% profit.

Scale drawing of points P, Q, R and S with north lines and bearings marked, showing the ranch split into two triangles.
Form 3 • Geometry

Form 3 P1 Q19 — Bearings & Scale Drawing

Bearings, right-angle trig and Pythagoras to find PS, a bearing and the ranch area.

Thumbnail showing three bells with intervals 9, 15 and 21 minutes and the LCM time calculation
Form 3 • Numbers

Form 3 P1 Q2 — Bells & LCM

Three bells and their LCM tell you exactly when they last chimed together.

Thumbnail showing a coordinate grid with three straight lines labelled L, P and Q and the question number 20.
Form 3 • Geometry

Coordinate Geometry: Lines L, P & Q

Find the equations of three related lines and the point where the perpendicular meets the parallel line.

A coordinate grid showing a small square ABCD being enlarged, reflected and rotated into new positions.
Form 3 • Geometry

Form 3 P1 Q21 — Combined Transformations

Enlarge, reflect and rotate a square, then name the single transformation that links the two images.

Cross-section diagram of a large cone with a smaller similar cone scooped out of its base, forming a conical hole.
Form 3 • Measurement

Cone with a Conical Hole

Use similar cones to find the hole radius, volume removed and total remaining surface area.

A speed–time graph of a cheetah rising from 15 m/s to a maximum, holding steady, then falling to zero at 40 seconds.
Form 3 • Measurement

Speed–Time Graph (Cheetah)

Read a cheetah's speed–time graph to find its top speed, accelerations and average speed.

Video thumbnail for Alliance Form 3 Paper 1 Question 24 on commission and percentages.
Form 3 • Numbers

Q24 — Commission & Percentages

Find monthly earnings from commission plus salary, then reverse the process to get total sales and units sold.

Video thumbnail showing a KCSE simultaneous equations word problem about the cost of hiring technicians and artisans.
Form 3 • Algebra

Form 3 P1 Q3 — Simultaneous Equations

Turn a hiring word problem into two equations and solve by elimination.

Video thumbnail showing a currency exchange question converting US dollars to Kenya shillings and then to British pounds.
Form 3 • Numbers

Currency Exchange: Buying vs Selling Rates

Convert $100,000 to shillings then to pounds using the correct bank rates.

Thumbnail showing a regular polygon with one interior angle labelled 3x and its exterior angle labelled x minus 20.
Form 3 • Geometry

Alliance F3 P1 Q5 — Angles of a Regular Polygon

Use angles on a straight line and the exterior-angle sum to find how many sides the polygon has.

Video thumbnail showing an index expression with fractional powers of 243, 125 and 9 being simplified to 75.
Form 3 • Algebra

Alliance F3 P1 Q6 — Laws of Indices

Simplify a fractional-power expression using the laws of indices — step by step to 75.

Video thumbnail showing the trigonometry equation sin(x+60) = cos 2x for Alliance Form 3 Paper 1 Question 8.
Form 3 • Trigonometry

Complementary Angles: Solving for tan(x+60)

Use the sine-cosine complementary rule to solve sin(x+60)=cos 2x, then find tan 70 degrees.

Thumbnail showing a closed cylinder with its radius equal to its height and the total surface area labelled 154 square centimetres.
Form 3 • Measurement

Cylinder Surface Area: Find the Diameter

Radius equals height and total surface area is 154 cm² — find the diameter to 2 d.p.

Ruler-and-compass construction of triangle ABC with AB 5 cm, a 120 degree angle at A, and BC 10 cm, with angle ABC marked.
Form 4 • Geometry

Triangle Construction (Q10)

Construct triangle ABC and measure angle ABC, confirmed by the sine rule.

Thumbnail showing KCSE 2025 Maths Paper 1 Question 11 on profit and loss, solving for the cost price of an item.
Form 4 • Numbers

KCSE 2025 P1 Q11 — Profit & Loss

Set up profit and loss equations, add them to eliminate the cost price, and find what the shopkeeper paid.

Thumbnail showing a histogram with three bars and the task to find missing frequencies for KCSE 2025 Maths Paper 1 Question 12.
Form 4 • Statistics

Histogram Frequencies (KCSE 2025 P1 Q12)

Find the two missing frequencies from histogram bar heights using frequency density.

Thumbnail showing a grid with triangle ABC, its reflected image points A dash and C dash, and a mirror line drawn between them.
Form 4 • Geometry

Reflection: Finding the Mirror Line

Use the perpendicular bisector to construct the mirror line and finish the reflected triangle.

Video thumbnail showing a trapezoidal prism being unfolded into its labelled net of four rectangles and two trapezium ends
Form 4 • Geometry

Net of a Prism

Unfold a trapezoidal prism into four rectangles and two trapezium ends to draw its labelled net.

Right-angled triangle ABC with point D on AC, showing AB = 8 cm, AD = 5 cm, and the area of triangle ABD marked as 10 square cm.
Form 4 • Trigonometry

KCSE 2025 Maths P1 Q15 — Trigonometry

Use a triangle's area to unlock a hidden angle, then find BC with tan.

Video thumbnail showing the curve y = 3x^2 - 4x with a tangent line drawn at point P(1, -1).
Form 4 • Calculus

Tangent to a Curve at a Point

Differentiate the curve, find the gradient at P, then form the tangent line.

Video thumbnail showing a lorry and a car travelling towards each other on a 160 km road, meeting at point C, for KCSE 2025 Maths Paper 1 Question 17.
Form 4 • Measurement

KCSE 2025 P1 Q17 — Speed, Distance & Time

Two vehicles meet on a 160 km road — find the meeting time, distance and the car's return speed.

Thumbnail showing a right pyramid mounted on a rectangular block with labelled dimensions for KCSE 2025 Maths Paper 1 Question 18.
Form 4 • Measurement

KCSE 2025 P1 Q18 — Volume & Surface Area

A right pyramid sits on a 6 by 6 by 10 block — find its volume, then the surface area of one cut half.

Coordinate grid showing line L1 through points A and B, a parallel line L2, and a perpendicular line L3 meeting L2 at point P.
Form 4 • Geometry

KCSE 2025 P1 Q19 — Coordinate Geometry

Gradients, parallel and perpendicular line equations, and the intersection point P.

Thumbnail for KCSE 2025 Maths Paper 1 Question 2 on ratio, showing an hourly rate being changed in the ratio 8 to 7.
Form 4 • Numbers

KCSE 2025 Maths P1 Q2 — Ratio

Change an hourly rate in the ratio 8:7 and find the pay for 10½ hours.

Video thumbnail showing KCSE 2025 Maths Paper 1 Question 20 on matrices, with the two lorry equations and the matrix solution.
Form 4 • Algebra

KCSE 2025 P1 Q20 — Matrices

Solve a sand transport problem using the matrix method and calculate the transporter's profit.

Video thumbnail showing a grid with points P and Q and the vector PQ drawn, labelled KCSE 2025 Maths Paper 1 Question 21 Vectors.
Form 4 • Geometry

KCSE 2025 P1 Q21 — Vectors

Column vector PQ, solving for scalars k and h, then the magnitude of ka.

Video thumbnail showing a constructed trapezium ABCD with an arc of centre A and radius 5 cm.
Form 4 • Geometry

KCSE 2025 P1 Q22 — Trapezium Construction

Construct trapezium ABCD, then work out the area lying outside the arc of centre A.

Thumbnail showing a frequency distribution table with the mean and median amounts spent on petrol highlighted.
Form 4 • Statistics

KCSE 2025 P1 Q23 — Mean & Median

Build a frequency table and estimate the mean and median money spent on petrol.

Thumbnail showing an indices equation with 4, 8 and 32 being rewritten as powers of 2 to solve for x.
Form 4 • Algebra

KCSE 2025 P1 Q3: Indices

Solve for x by rewriting every term as a power of 2, then comparing indices.

Diagram of an L-shaped plot of land ABCDEF with an added rectangle BCDG, forming a larger rectangle AGEF, on the video thumbnail.
Form 4 • Calculus

KCSE 2025 P1 Q24 — Maximum Area

Maximise the area of a plot of land using differentiation.

Video thumbnail showing KCSE 2025 Maths Paper 1 Question 6 on finding the highest common factor of 240 and 150.
Form 4 • Numbers

KCSE 2025 P1 Q6 — Highest Common Factor

Find the least number of families by using the HCF of 240 kg and 150 kg.

Thumbnail showing a rectangular farm on a grid with a dotted flooded section shaded blue
Form 4 • Measurement

Area by Counting Squares

Estimate the un-flooded area of a rectangular farm by counting grid squares.

Thumbnail showing the double inequality with (5 - 2x)/3 and the label Q4 Inequalities KCSE 2025 Maths Paper 1.
Form 4 • Algebra

KCSE 2025 P1 Q4: Double Inequality

Split a double inequality into two parts, solve each, then combine to get 1 < x ≤ 4.

Video thumbnail showing a wall clock with the KCSE 2025 Maths Paper 1 Question 9 label on time lost by a slow clock.
Form 4 • Measurement

KCSE 2025 P1 Q9 — Slow Clock

A clock loses 18 seconds an hour — what does it read on Saturday at 11:20 am?

Thumbnail showing a cone with base radius 7 cm, vertical height, and slant height, formed from a 550 square centimetre sector.
Form 4 • Measurement

Cone from a Sector

Roll a 550 cm² sector into a cone of radius 7 cm and find its height.