O/L — Grade 10 & 11

O/L Mathematics (NIE syllabus)

G.C.E. O/L Mathematics in Sri Lanka follows the National Institute of Education (NIE) syllabus. The NIE's Grade 10 Teachers' Guide, implemented from 2015, sets out 31 lessons over 190 teaching periods, split across the three school terms: 47 periods in Term 1 (perimeter, square root, fractions, binomial expressions, congruency, area, factors of quadratic expressions, triangles, inverse proportion, data representation), 71 in Term 2 and 72 in Term 3. The single largest Grade 10 lessons are Triangles, Frequency Distributions and Constructions, at 10 periods each. This is the Sri Lankan G.C.E. (O/L) syllabus, not Cambridge or Edexcel IGCSE Mathematics.

Find your unit, not your term

Your school may teach these in a different order. The order below is the NIE's own proposed lesson sequence; pick the lesson you are on.

Grade 10: the NIE's own lesson sequence, with the teaching periods it gives each lesson.

Term (NIE)	#	Lesson (NIE name)	Periods	Competency levels	Free pages	Source
Grade 10 · Term 1	1	Perimeter	4	7.1	Notes · Practice	[S1] p. 32
Grade 10 · Term 1	2	Square Root	4	1.1	Notes · Practice	[S1] p. 32
Grade 10 · Term 1	3	Fractions	4	3.1	Notes · Practice	[S1] p. 32
Grade 10 · Term 1	4	Binomial Expressions	4	14.1	Notes · Practice	[S1] p. 32
Grade 10 · Term 1	5	Congruency	5	23.3	Notes · Practice	[S1] p. 32
Grade 10 · Term 1	6	Area	4	8.1	Notes · Practice	[S1] p. 32
Grade 10 · Term 1	7	Factors of Quadratic Expressions	4	15.1	Notes · Practice	[S1] p. 32
Grade 10 · Term 1	8	Triangles	10	23.1, 23.2, 23.4, 23.5	Notes · Practice	[S1] p. 32
Grade 10 · Term 1	9	Inverse Proportion	5	4.1	Notes · Practice	[S1] p. 32
Grade 10 · Term 1	10	Data Representation	3	28.2	Notes · Practice	[S1] p. 32
Grade 10 · Term 2	11	Least Common Multiple of Algebraic Expressions	8	16.1, 16.2	Notes · Practice	[S1] p. 32
Grade 10 · Term 2	12	Algebraic Fractions	7	5.1, 5.2	Notes · Practice	[S1] p. 32
Grade 10 · Term 2	13	Percentages	8	17.1, 17.2, 17.3	Notes · Practice	[S1] p. 32
Grade 10 · Term 2	14	Equations	7	23.6, 23.7	Notes · Practice	[S1] p. 32
Grade 10 · Term 2	15	Parallelograms I	9	23.8, 23.9, 23.10	Notes · Practice	[S1] p. 32
Grade 10 · Term 2	16	Parallelograms II	8	30.1, 30.2	Notes · Practice	[S1] p. 32
Grade 10 · Term 2	17	Sets	5	6.1, 6.2	Notes · Practice	[S1] p. 32
Grade 10 · Term 2	18	Logarithms I	5	6.3, 6.4	Notes · Practice	[S1] p. 32
Grade 10 · Term 2	19	Logarithms II	9	20.1, 20.2, 20.3	Notes · Practice	[S1] p. 32
Grade 10 · Term 2	20	Graphs	5	12.1	Notes · Practice	[S1] p. 32
Grade 10 · Term 2	21	Rate	not printed	—	Notes · Practice	[S1] p. 32
Grade 10 · Term 3	22	Formulae	3	19.1	Notes · Practice	[S1] p. 32
Grade 10 · Term 3	23	Arithmetic Progressions	7	2.1, 2.2	no page yet	[S1] p. 32
Grade 10 · Term 3	24	Algebraic Inequalities	6	18.1	Notes · Practice	[S1] p. 32
Grade 10 · Term 3	25	Frequency Distributions	10	28.1, 29.1	Notes · Practice	[S1] p. 32
Grade 10 · Term 3	26	Chords of a Circle	6	24.1, 24.2	Notes · Practice	[S1] p. 32
Grade 10 · Term 3	27	Constructions	10	27.1, 27.2, 27.3	Notes · Practice	[S1] p. 32
Grade 10 · Term 3	28	Surface Area and Volume	9	8.2, 8.3, 10.1, 10.2	Notes · Practice	[S1] p. 32
Grade 10 · Term 3	29	Probability	8	31.1, 31.2	Notes · Practice	[S1] p. 32
Grade 10 · Term 3	30	Angles in a Circle	8	24.3, 24.4	no page yet	[S1] p. 32
Grade 10 · Term 3	31	Scale Diagrams	5	13.1	no page yet	[S1] p. 32

Lessons, periods, competency levels and terms from [S1] p. 32. Lesson 11 is printed as two rows of 4 periods (competency levels 16.1 and 16.2) and is shown here as one lesson of 8. Lesson 21, Rate, has no periods printed; the term subtotals (47, 71, 72) and the total (190) add up without it. The NIE's “Graphs” and “Algebraic Inequalities” are published on this site as Linear Relationships and Linear Inequalities. Arithmetic Progressions, Angles in a Circle and Scale Diagrams have no page yet.

Grade 11: the NIE's own lesson sequence

Grade 11: the NIE's own lesson sequence, with the teaching periods it gives each lesson.

Term (NIE)	#	Lesson (textbook name)	Periods	Competency levels	Free pages	Source
Grade 11 · Term 1	1	Real Numbers	10	1.1, 1.2, 1.3	Notes · Practice	[S3] p. 43
Grade 11 · Term 1	2	Indices and Logarithms I	8	6.1, 6.2	Notes · Practice	[S3] p. 43
Grade 11 · Term 1	3	Indices and Logarithms II	6	6.3, 6.4 (part)	Notes · Practice	[S3] p. 43
Grade 11 · Term 1	4	Surface Area of Solids	5	8.1	Notes · Practice	[S3] p. 43
Grade 11 · Term 1	5	Volume of Solids	5	10.1	Notes · Practice	[S3] p. 43
Grade 11 · Term 1	6	Binomial Expressions	4	14.1	no page yet	[S3] p. 43
Grade 11 · Term 1	7	Algebraic Fractions	4	16.1	no page yet	[S3] p. 43
Grade 11 · Term 1	8	Areas of Plane Figures between Parallel Lines	12	23.1, 23.2	Notes · Practice	[S3] p. 43
Grade 11 · Term 2	9	Percentages	6	5.1, 5.2	no page yet	[S3] p. 43
Grade 11 · Term 2	10	Share Market	5	5.3	Notes · Practice	[S3] p. 43
Grade 11 · Term 2	11	The Midpoint Theorem	5	23.6	Notes · Practice	[S3] p. 43
Grade 11 · Term 2	12	Graphs	12	20.1, 20.2, 20.3	Notes · Practice	[S3] p. 43
Grade 11 · Term 2	13	Equations	10	17.1, 17.2	no page yet	[S3] p. 43
Grade 11 · Term 2	14	Equiangular Triangles	12	23.3, 23.4	Notes · Practice	[S3] p. 43
Grade 11 · Term 2	15	Data Representation and Interpretation	12	28.1, 28.2, 28.3, 29.1	Notes · Practice	[S3] p. 43
Grade 11 · Term 2	16	Geometric Progressions	6	2.1	Notes · Practice	[S3] p. 43
Grade 11 · Term 3	17	Pythagoras' Theorem	4	23.5	Notes · Practice	[S3] p. 43
Grade 11 · Term 3	18	Trigonometry	12	13.1, 13.2, 6.4 (part)	Notes · Practice	[S3] p. 43
Grade 11 · Term 3	19	Matrices	8	20.4	Notes · Practice	[S3] p. 43
Grade 11 · Term 3	20	Inequalities	6	18.1	Notes · Practice	[S3] p. 43
Grade 11 · Term 3	21	Cyclic Quadrilaterals	10	24.1, 24.2	Notes · Practice	[S3] p. 43
Grade 11 · Term 3	22	Tangents	10	24.3, 24.4, 24.5	Notes · Practice	[S3] p. 43
Grade 11 · Term 3	23	Constructions	5	27.1, 27.2	no page yet	[S3] p. 43
Grade 11 · Term 3	24	Sets	6	30.1	no page yet	[S3] p. 43
Grade 11 · Term 3	25	Probability	7	31.1	no page yet	[S3] p. 43

Lessons, periods, competency levels and terms from [S3] p. 43 (Term 1 = 54, Term 2 = 68, Term 3 = 68, total 190); lesson names from the Grade 11 textbook [S4]. The guide prints lesson 11 as “Central limit theorem” and lesson 15 as “Data representation and prediction”; the textbook names them The Midpoint Theorem and Data Representation and Interpretation. Binomial Expressions, Algebraic Fractions, Percentages, Equations, Constructions, Sets and Probability have no Grade 11 page yet. This site publishes Pythagoras' Theorem under Grade 11 Term 2; the NIE places it in Term 3, and the table follows the NIE.

Term-by-Term Breakdown

Try one question — no account needed

Model question — written by Idasara, modelled on the G.C.E. (O/L) Mathematics examination pattern. NIE Grade 10, lesson 13: Percentages.

A trader buys a television for Rs. 50,000 and sells it at a profit of 15%. What is the selling price of the television?

A) Rs. 55,000
B) Rs. 57,500
C) Rs. 60,000
D) Rs. 58,000

Check my answer

Correct answer: B) Rs. 57,500

Profit amount = 15% of 50,000 = (15/100) × 50,000 = Rs. 7,500. Selling Price = Cost Price + Profit = 50,000 + 7,500 = Rs. 57,500.

Show worked solution

Step 1: Calculate profit percentage on cost: Profit = 50,000 × 0.15 = Rs. 7,500. Step 2: Add profit to cost: Selling Price = 50,000 + 7,500 = Rs. 57,500. (Alternatively: Selling Price = 50,000 × 1.15 = Rs. 57,500). Answer: Rs. 57,500.

Get your own answer marked

How the exam works

G.C.E. O/L Mathematics is set by the Department of Examinations and sat at the end of 11 years of school, on the Grade 10 and Grade 11 syllabi. There are two papers, each marked out of 100. Paper I takes 2 hours: Part A is 25 short questions at 2 marks each, and Part B is 5 structured questions at 10 marks each, none of them on algebra or geometry. Paper II takes 3 hours and has two parts of 6 questions; in each part you answer 5, at 10 marks each. Part A has no geometry questions and Part B no algebra questions. ([S5] pp. 08 and 32; [S6] p. 1.)

Department of Examinations — G.C.E. (O/L) 2024 Evaluation Report, Mathematics (Sinhala, PDF)

Where should I start?

One short block per reader, one link each. These are suggestions, not rules; the tables above are the map.

Starting Grade 10 — The NIE's first term opens with perimeter, square root and fractions. → Perimeter notes
In Grade 11 — Work the practice set lesson by lesson, then get your answers marked. → All O/L Maths practice
Sitting the examination again — Start from the method, not the first lesson. → How to be ready for O/L Maths
Studying in Sinhala → සිංහල
Studying in Tamil → தமிழ்
A parent — What your child gets, and what it costs. → Pricing · For parents

Free study resources by topic

Guides

Questions students ask

How many lessons are there in Grade 10 Maths, and how are they spread over the terms?

The NIE's Grade 10 guide sets out 31 lessons over 190 periods: 47 periods in the first term, 71 in the second and 72 in the third. ([S1] p. 32)

Which Grade 10 lessons get the most teaching time?

Triangles, Frequency Distributions and Constructions, at 10 periods each; then Parallelograms I, Logarithms II and Surface Area and Volume at 9 each. ([S1] p. 32)

Do I have to study the lessons in this order?

No. The NIE calls it a proposed lesson sequence, so your school may teach them in a different order — which is why this page lists the lesson, not just the term. ([S1] p. 32, “2.0 Lesson Sequence”)

When is the O/L Maths paper sat?

The Department of Examinations holds the O/L at the end of 11 years of school, on the Grade 10 and Grade 11 syllabi. The year in the exam's name and the sitting can differ: the 2024 O/L was sat in March 2025, with both Maths papers on 24 March (Paper I 08:30–10:30, Paper II 13:00–16:10). Check the Department's timetable for your year. ([S6] p. 1; [S7])

Is this the same as Cambridge or Edexcel IGCSE Maths?

No. This is the Sri Lankan G.C.E. (O/L) syllabus published by the NIE, with its own lessons, its own period weights and its own examination. ([S1] title page)