Sec 3 in 2027: New Subjects, Chemistry and Physics Topics, SEC Run-Up

Sec 3 is the year Chemistry, Physics, Biology and Additional Mathematics become separate subjects, and the start of the two-year SEC course. For the 2027 Sec 3 cohort, that course ends with the SEC in September to November 2028 and results in January 2029.

This guide sets out what is on the syllabus, subject by subject, with topic tables taken from the SEAB and MOE syllabus documents. It covers how Sec 3 is assessed, what changes from Sec 2, where students usually struggle and what parents can do, and closes with a dated timeline to the 2028 SEC. If your child already finds Chemistry hard and needs a catch-up plan, our Sec 3 Chemistry wake-up call covers that. This page is the map of the whole year.

Who is in Sec 3 in 2027?

All three groups are Full SBB cohorts, so each subject is taken at G1, G2 or G3, and the SEC certificate lists every subject with its level. SEAB has published SEC syllabuses for the 2027 exam. The 2028 syllabuses were not yet on SEAB's site when we checked on 7 November 2026, so the tables below use the 2027 versions, which is what Sec 3 teachers are working from.

Sources: SEAB, Secondary Education Certificate and SEAB, 2027 G3 syllabuses. Our SEC 2027 explainer covers the change from the O-Level.

What changes from Sec 2 to Sec 3

Upper secondary keeps five compulsory subjects: English, Mother Tongue (or Higher Mother Tongue), Mathematics, Science and Humanities. What changes is how they are split.

Three things catch families out:

1. The content jumps in depth, not just volume. Lower Secondary Science names atoms and molecules and shows acids reacting with metals without equations. Sec 3 Chemistry expects balanced ionic equations with state symbols and mole calculations.
2. A-Math is new and fast. It assumes all of the G3 E-Math syllabus, so it leans on Sec 1 and Sec 2 algebra from the first week.
3. Subject levels can still move. Under Full SBB, MOE says students may take a subject at a less demanding level after school review, and move back up as they gain confidence. Electives can also be taken at a level the student chooses. The school has the final say.

Sources: MOE, Full SBB secondary school experience, MOE, Full SBB FAQ and MOE, Lower Secondary Science G2/G3 syllabus (PDF). For a fuller look at levels, see choosing G1, G2 or G3 subject levels.

Sec 3 Chemistry topics (G3 Chemistry, K324)

G3 Chemistry K324 replaces O-Level Chemistry 6092. We compared the two syllabus documents: the 12 topics, their sub-topics and the three papers are the same. The table is the syllabus order.

How it is examined in Sec 4: Paper 1 is 40 multiple-choice questions (1 hour, 30%). Paper 2 is structured and free response (1 hour 45 minutes, 80 marks, 50%), including a data-based question. Paper 3 is a practical (1 hour 50 minutes, 40 marks, 20%) with a planning element and printed Notes for Qualitative Analysis.

Download the official syllabus: SEAB K324 G3 Chemistry syllabus 2027 (PDF). It lists every learning outcome, the practical apparatus and the Notes for Qualitative Analysis printed in the exam. We compared it with SEAB 6092 O-Level Chemistry syllabus 2026 (PDF). Our O-Level Chemistry syllabus page goes deeper topic by topic.

Which chemistry topics fall in Sec 3?

MOE and SEAB set a two-year syllabus and do not split it by year. Each school writes its own scheme of work, so the Sec 3 and Sec 4 split varies. Many schools work broadly in syllabus order, because the mole (topic 4) needs bonding and formulae first, and qualitative analysis needs salts and acids.

For a real example, one secondary school's Sec 3 timed practice schedule for Term 3 of 2026 tested Pure Chemistry on the mole, acids and bases, salts and qualitative analysis, and Combined Science (Chemistry) on chemical formulae and equations, the mole and acids and bases. That puts topics 1 to 6 in Sec 3 at that school, with redox, the periodic table, energetics, rates, organic chemistry and air quality left for late Sec 3 or Sec 4. Ask your school for its scheme of work in Term 1.

Source: a secondary school's 2026 Sec 3 Term 3 timed practice schedule (PDF).

Salt preparation: which method to use

The syllabus expects students to suggest a method for making a given salt. The choice depends on whether the salt is soluble and on what you start with.

To pick the method, students need the solubility rules the syllabus lists:

Two quick examples. Copper(II) sulfate crystals: add excess copper(II) oxide to warm dilute sulfuric acid, filter, then crystallise. Barium sulfate: mix aqueous barium nitrate with dilute sulfuric acid, then filter, wash and dry the white precipitate.

Redox: the definitions students must know

Redox is topic 7. The syllabus defines it in three ways, and exam questions can use any of them.

An oxidising agent causes something else to be oxidised, so it is itself reduced. A reducing agent causes something else to be reduced, so it is itself oxidised.

Worked example. In Zn + CuSO₄ gives ZnSO₄ + Cu, zinc goes from oxidation state 0 to +2, so zinc is oxidised and is the reducing agent. Copper goes from +2 to 0, so Cu²⁺ is reduced and is the oxidising agent.

Two lab tests are in the syllabus. Aqueous potassium iodide turns from colourless to brown when an oxidising agent is added. Acidified potassium manganate(VII) turns from purple to colourless when a reducing agent is added. Electrolysis and simple cells come later in the same topic.

Practical skills and qualitative analysis

Paper 3 is worth 20% of the grade, and SEAB names four skill areas. Planning an experiment carries 15% of the practical marks. Manipulation, measurement and observation, presentation of data, and analysis, conclusions and evaluation carry the other 85%. No notes or textbooks are allowed, but the Notes for Qualitative Analysis are printed in the paper.

The syllabus lists the kinds of practical that can be set: acid-base titration, speed of reaction, separation (chromatography, filtration, distillation), salt preparation, gas collection, inorganic qualitative analysis and simple organic tests. SEAB also sets the expected precision: burette readings to the nearest 0.05 cm³, and two titres within 0.20 cm³ of each other. In qualitative analysis, students use about 1 to 2 cm³ of solution, add reagent slowly until no further change, and say at what stage a change happens.

These are the qualitative analysis results students need, from SEAB's Notes for Qualitative Analysis:

Our free qualitative analysis notes have these tables as a printable sheet.

G2 Chemistry: how it differs from G3

There is no separate G2 Chemistry subject. At G2, chemistry is half of G2 Science: K223 (Physics, Chemistry) or K225 (Chemistry, Biology).

A student moving from G2 to G3 Chemistry has to pick up redox, energetics, rates and the harder mole calculations, so ask the school how it bridges the gap.

Source: SEAB K223, K224, K225 G2 Science syllabus 2027 (PDF).

How to study Sec 3 Chemistry

Data-based questions are worth 8 to 12 marks in Paper 2 and test reading of unfamiliar information, so practise graphs and tables, not only recall. Our Sec 3 Chemistry wake-up call has a six-week catch-up plan if your child is already behind.

Free Sec 3 Chemistry notes and practice papers

• Our free sheets, no sign-up needed: the O-Level Chemistry periodic table, the qualitative analysis notes, and the E-Math, A-Math and Physics formula sheets. All are on our free resources page.
• The SEAB syllabus PDF above is free and is the most exact list of what can be tested.
• Student Learning Space (SLS). MOE says every student in the national school system has access to SLS, with curriculum-aligned resources from primary to pre-university. Ask the chemistry teacher which SLS lessons match each chapter.
• Past papers. SEAB had not posted a specimen paper for K324 when we checked on 7 November 2026. Because K324 keeps the 6092 topics and papers, O-Level Chemistry past-year papers and school exam papers remain good practice. Use topical sets in Sec 3 and full papers from late Sec 3.

Practice questions with answers

Try these before checking. They cover topics 4 to 7 and use relative atomic masses H 1, O 16, S 32.

1. How many moles are in 4.9 g of sulfuric acid, H₂SO₄?
2. What volume does 0.25 mol of oxygen occupy at room temperature and pressure?
3. Which method would you use to prepare potassium nitrate crystals, and from what?
4. 25.0 cm³ of 0.100 mol/dm³ sodium hydroxide is neutralised by 20.0 cm³ of hydrochloric acid. What is the concentration of the acid?
5. In Mg + 2HCl gives MgCl₂ + H₂, which substance is oxidised?
6. A solution gives a light blue precipitate with aqueous ammonia, which dissolves in excess to give a dark blue solution. Which cation is present?
7. A gas relights a glowing splint. What is it?

Sec 3 Physics topics (G3 Physics, K323)

The exam has the same shape as Chemistry: Paper 1 multiple choice (1 hour, 40 marks, 30%), Paper 2 structured and free response (1 hour 45 minutes, 80 marks, 50%) and Paper 3 practical (1 hour 50 minutes, 40 marks, 20%).

In the same school's 2026 Term 3 practice schedule, Sec 3 Pure Physics covered pressure, energy, the kinetic particle model, thermal processes and thermal properties of matter. So that school had topics 1 to 9 done by August of Sec 3, with waves, electricity, magnetism and radioactivity ahead.

Source: SEAB K323 G3 Physics syllabus 2027 (PDF). See our O-Level Physics syllabus page and SEC Physics A1 guide.

Sec 3 Biology topics (G3 Biology, K325)

Papers and weightings match Physics and Chemistry: 30% multiple choice, 50% structured, 20% practical. In the same school's 2026 schedule, Sec 3 Biology was on transport, respiration and excretion in humans by Term 3.

Source: SEAB K325 G3 Biology syllabus 2027 (PDF). Our SEC Biology A1 guide has revision methods.

Combined Science: what is in it and what is left out

Students who do not take two or three pure sciences usually take Combined Science, which pairs two of the three. There are three versions at G3.

Paper 1 is 40 multiple-choice questions split roughly evenly between the two sciences (1 hour, 20%). Each science paper is 1 hour 15 minutes, 65 marks, 32.5%. Paper 5 is a 1 hour 30 minute practical test worth 15%.

The topics are a lighter version of the pure syllabuses. These are the main differences we found reading the two side by side:

Combined Science is a full G3 subject and counts as a science for JC and polytechnic aggregates. The trade-off is that a student who later wants H2 Chemistry or Physics in JC meets more new content there.

Source: SEAB K326, K327, K328 G3 Science syllabus 2027 (PDF). Our SEC Combined Science guide compares the options in more detail.

Sec 3 Maths: E-Math and A-Math

E-Math (G3 Mathematics, K310)

MOE's G3 Mathematics syllabus lists content for Sec 1, Sec 2 and then Sec 3 and 4 together. This is the content that is new in upper secondary.

The SEC exam is two papers of 2 hours 15 minutes, each 90 marks and 50%. Paper 2's last question applies maths to a real-world scenario.

Sources: MOE G2 and G3 Mathematics syllabuses (PDF) and SEAB K310 G3 Mathematics syllabus 2027 (PDF).

A-Math (G3 Additional Mathematics, K341)

Two papers, each 2 hours 15 minutes, 90 marks and 50%. Each school decides the order. Because calculus builds on the algebra and trigonometry topics, it tends to come later, so ask for the scheme of work.

Source: SEAB K341 G3 Additional Mathematics syllabus 2027 (PDF). See O-Level Additional Mathematics and E-Math vs A-Math if your child is deciding whether to keep A-Math.

Humanities electives and other subjects

At G2 and G3, Humanities in upper secondary is Social Studies plus one elective. Students can also take a second full humanities subject.

The Social Studies paper has a 35-mark source-based case study and 15 marks of structured-response questions, set across three Issues: citizenship and governance, living in a diverse society, and being part of a globalised world.

Other G3 electives on SEAB's list include Principles of Accounts (K342), Computing (K349), Nutrition and Food Science (K346), Design & Technology (K345), Art (K347) and Music (K350).

Sources: SEAB, 2027 G3 syllabuses and SEAB K335 Humanities syllabus 2027 (PDF). Our guides to Social Studies SBQ and SRQ, History SBQ, Geography and Literature cover the skills. Every code is listed in SEC syllabus codes for 2027.

How Sec 3 is assessed

MOE removed mid-year exams at every primary and secondary level by 2023. Sec 3 is graded by the school, not by SEAB.

Each school decides the weights and the dates, so ask for the assessment plan in Term 1. The EOY is the first time most students sit full SEC-style papers, including a long structured paper in each science. Our guide to WA1, WA2 and SA2 explains how school assessments are put together.

Source: MOE, Nurturing confident, resilient learners (7 Mar 2022).

2027 term dates

MOE published the 2027 calendar on 14 July 2026. These dates are final.

Schools are closed on Tuesday 9 February and Monday 3 May (days in lieu), and secondary schools also have Monday 5 July (after Youth Day), Tuesday 10 August (after National Day) and Friday 3 September (Teachers' Day) off. Children's Day on 8 October is a primary school holiday only.

Source: MOE, school terms and holidays for 2027. Our 2027 school holidays guide has every level.

Common struggles, with worked examples

1. The mole concept

The mole is the first topic where chemistry becomes arithmetic. Students who memorised Lower Secondary Science facts suddenly have to set up a chain of steps.

Worked example. What mass of carbon dioxide forms when 10.0 g of calcium carbonate is heated, and what volume is that at room temperature and pressure?

1. Write the balanced equation: CaCO₃(s) gives CaO(s) + CO₂(g).
2. Find Mr of CaCO₃: 40 + 12 + (3 × 16) = 100.
3. Moles of CaCO₃ = 10.0 ÷ 100 = 0.100 mol.
4. The equation is 1 : 1, so moles of CO₂ = 0.100 mol.
5. Mass of CO₂ = 0.100 × 44 = 4.40 g.
6. Volume of CO₂ = 0.100 × 24 = 2.40 dm³.

Most lost marks come from step 1 (an unbalanced equation) or step 4 (skipping the mole ratio). Insist on writing every step, every time.

2. A-Math algebra

A-Math moves quickly, and every later topic leans on algebra. A student shaky on factorising or expanding brackets from Sec 2 feels it in the first month.

Worked example. Find the values of k for which the line y = kx + 1 is a tangent to the curve y = x² + 3.

1. Set the equations equal: x² + 3 = kx + 1.
2. Rearrange: x² − kx + 2 = 0.
3. A tangent touches once, so the discriminant is zero: k² − 4(1)(2) = 0.
4. So k² = 8, giving k = 2√2 or k = −2√2.

This one question uses three syllabus topics: quadratics (A2), the discriminant and surds (A3). That is why gaps in one A-Math topic spread to others.

3. Physics graphs

Kinematics is second in the syllabus order, so it often comes early in Sec 3. The syllabus expects students to plot and read displacement-time and velocity-time graphs. Many students read the axes wrongly or forget what the area means.

Worked example. A car accelerates from rest to 20 m/s in 5 s, then travels at 20 m/s for 10 s. Find its acceleration and the total distance.

1. Acceleration = change in velocity ÷ time = 20 ÷ 5 = 4 m/s².
2. Distance is the area under the velocity-time graph.
3. Triangle (0 to 5 s): ½ × 5 × 20 = 50 m.
4. Rectangle (5 to 15 s): 10 × 20 = 200 m.
5. Total distance = 250 m.

The rule to drill: on a velocity-time graph, the gradient is acceleration and the area is distance. On a displacement-time graph, the gradient is velocity.

Other bumps worth expecting

• Ionic equations and state symbols. Required in Chemistry from topic 4 onwards, and often missed under time pressure.
• Practical skills. Science practicals are worth 20% of each pure science (15% of Combined Science), and Chemistry Paper 3 includes planning an experiment. Students who only revise theory lose marks here.
• Workload. Sec 3 adds several new exam subjects at once. A weekly plan that touches each one helps more than cramming before each WA.
• Social Studies source questions. These reward a set answer structure, which takes practice to learn.

Our O-Level Chemistry A1 guide and A-Math A1 guide go further on technique.

How parents can help

You do not need to know the chemistry yourself. Asking your child to explain one topic to you each week, in their own words, is a quick check on what they really understand. If one subject keeps slipping across two or three WAs, that is the time to talk to the subject teacher, and to consider extra help such as Sec 3 Chemistry tuition, Sec 3 Physics tuition, Sec 3 Maths tuition or Sec 3 English tuition.

Timeline to the 2028 SEC and the 2029 PSE

Dates marked expected have not been published. Each sits beside the date the 2027 cohort or the 2026 O-Level cohort actually had.

Sources: MOE, PSE, SEAB, Secondary Education Certificate, MOE DSA-JC and SEAB 2026 O-Level timetable (PDF). Our PSE 2028 guide and L1R4 guide explain how the aggregates work. MOE lets students combine results from up to two exam years for the PSE.