Last reviewed: 24 October 2026
Mathematics is the subject Grade 9 learners worry about most before KJSEA, and the one where steady practice shows up most clearly in results. The junior school Mathematics curriculum is organised into five strands: Numbers, Algebra, Measurements, Geometry, and Data Handling and Probability. This guide lists the Grade 9 topics in each strand that deserve the most revision time, the mistakes that cost marks, and a practical way to revise them.
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Numbers
Key topics are cubes and cube roots, indices and logarithms, and compound proportions and rates of work. Learners must know the laws of indices well: when multiplying powers of the same base, add the indices (2³ × 2⁴ = 2⁷); when dividing, subtract them; and a power raised to a power multiplies them. Logarithm questions at this level usually test the link between indices and logs, for example that log₁₀ 1000 = 3 because 10³ = 1000.
Algebra
Revise matrices basics where taught, the equation of a straight line, linear inequalities and factorising quadratic expressions. For straight lines, the gradient between (1, 2) and (3, 8) is (8 − 2) ÷ (3 − 1) = 3, and learners should be able to write the full equation y = 3x − 1 from that. For inequalities, the most common error is forgetting to reverse the sign when multiplying or dividing by a negative number. For factorising, x² + 5x + 6 = (x + 2)(x + 3) because 2 + 3 = 5 and 2 × 3 = 6.
Measurements
This strand carries a lot of practical, competency-style questions. Revise area of circles and composite shapes, volume of prisms, cylinders and cones, mass, volume, weight and density, time and distance, and money. Money questions cover VAT (16% in Kenya), import duty, simple and compound interest, hire purchase, commission and currency conversion. A typical slip is calculating the VAT but forgetting to add it to the original price. Simple interest is principal × rate × time ÷ 100, so KSh 20,000 at 10% for three years earns KSh 6,000.
Geometry
Focus on coordinates and graphs, scale drawing and bearings, similarity and enlargement, and trigonometry (sine, cosine and tangent of acute angles). Bearings are always measured clockwise from north and written with three figures, such as 045° rather than 45°. In similarity, if lengths are multiplied by a scale factor k, areas are multiplied by k² — a frequent trap.
Data Handling and Probability
Learners should be able to find the mean, median and mode, draw and read frequency tables and graphs, and calculate simple probabilities. The probability of an event is the number of favourable outcomes divided by the total number of equally likely outcomes, and it always lies between 0 and 1.
A revision method that works
- Diagnose: take a ten-question round of the Grade 9 CBC Challenge in Mathematics and note the topics it flags.
- Learn: revise one flagged topic per day from notes on the Grade 9 hub, working at least five examples by hand.
- Apply: each weekend, do one section of a Grade 9 Mathematics revision paper under timed conditions.
- Review: mark it, add errors to an error log, and retest the same topics the following week.
Exam habits
- Show working. Method marks can rescue a wrong final answer.
- Write units in every answer: cm², m³, KSh, km/h.
- Estimate first. If a shopkeeper’s profit comes out larger than the selling price, something has gone wrong.
- Know how to use a calculator for powers, roots and trigonometric ratios before exam day.
Check the KJSEA timetable to plan the final weeks. CBC Guides is an independent revision site; our questions are written by our team and checked by a teacher, and we are not KNEC or KICD.