In the new lower secondary curriculum, your Chemistry marks do not come from memorising facts alone. Your teacher assesses you on five "elements of construct": big ideas about what a learner should appreciate or understand. For each one, marks are awarded against clear criteria. If you know those criteria, you know exactly what to write, show and explain to earn full marks. This guide breaks down all five.
What is an element of construct?
An element of construct is a big idea in a subject that a learner is expected to appreciate or understand by the end of the course. Each one is written as a statement, such as "The learner appreciates the contribution of chemistry to our economy." It tells you what you should be able to show, not just what you should memorise.
Every element of construct comes with three parts:
- Areas covered: the topics and examples it can be assessed on (for instance, the manufacture of cement or sulphuric acid).
- Basis of assessment: the things you must show, such as raw materials, the process, side effects and benefits.
- Criteria and scores: a table that says exactly how many marks each level of answer earns, from 0 up to the maximum.
In S4 Chemistry there are five elements of construct. Because the scoring is written out in advance, you can check your own work against it before you hand it in.
What changed from the old curriculum
The old O-Level curriculum was content-based: learners studied topics, then proved how much they remembered in end-of-term and final exams. The new lower secondary curriculum is competence-based: it asks what you can do with what you have learned. Here is how the two compare:
| Area | Old curriculum | New curriculum |
|---|---|---|
| Focus | Covering content and remembering facts | Building competences and skills, and applying knowledge to real life |
| How you are assessed | Mainly end-of-term exams and the final Senior Four exam | Class-based assessment across the four-year cycle, plus project work and the end-of-cycle exam |
| Final result | Based on the final national exam | 20% continuous assessment and 80% end-of-cycle exam |
| Grading | Numbers 1 to 9 (distinctions, credits, pass, fail) | Letters A to E, each with a description of what the learner can do |
| Skills | Mostly knowledge of content | Also communication, critical thinking, problem-solving, collaboration and decision-making |
| Missing work | You could still be graded from the final exam | No project or continuous assessment score in a subject means no grade in that subject |
What this means for you in Chemistry: you are marked on how well you use chemistry, for example by explaining how an industrial process works, judging a food additive, planning an experiment and analysing results. That is exactly what the five elements of construct measure.
1. The learner appreciates the contribution of chemistry to our economy
This construct is about how industry uses chemistry. You pick a process and show you understand how it works and why it matters.
Processes you can be assessed on
What to cover
- Raw materials used in the process.
- Process of production, including the vessel (V), chemical process (Cp), conversion to the desired product (Cd), coherence (Ch) and purification (Pr).
- Side effects of the process and how to reduce them.
- Social benefits of the product.
How it is scored (maximum 11)
| Basis | Criteria | Score |
|---|---|---|
| A. Raw materials | All raw materials | 2 |
| Any one raw material | 1 | |
| No raw material | 0 | |
| B. Process of production | Process with all of V, Cp, Ch, Pr | 3 |
| Process with any three of V, Cp, Ch, Pr | 2 | |
| Process with any one of V, Cp, Ch, Pr | 1 | |
| No process of production | 0 | |
| C. Side effects and mitigation | One danger identified, explained and mitigated | 3 |
| One danger identified and explained, OR identified and mitigated, OR explained and mitigated | 2 | |
| One danger identified, OR explained, OR mitigated | 1 | |
| Nothing identified, explained or mitigated | 0 | |
| D. Social benefits | One benefit identified, with its effect and its impact | 3 |
| One benefit with any two of: identified, effect, impact | 2 | |
| One benefit identified, OR effect, OR impact | 1 | |
| No social benefit identified | 0 |
2. The learner appreciates the application of chemistry in daily life
Here you look at products you meet every day and judge them.
Areas covered
- Food additives: flavour enhancers, antioxidants, acidity regulators, bulking agents, colours, emulsifiers, gelling agents, glazing agents, preservatives, raising agents, sweeteners, thickeners, whitening agents, humectants.
- Medicines: herbal medicines, analgesics, antibiotics, antimalarials, antiseptics, antipyretics, stimulants, antidepressants, antipsychotics, tranquilizers, mood stabilisers, anticonvulsants, hormone replacements, oral contraceptives, statins and more.
- Nuclear processes: fission, fusion, half-life and radioactive decay.
- Detergents: soapy and soapless.
How it is scored (maximum 8)
| Basis | Criteria | Score |
|---|---|---|
| A. Category/type of product | Product and its category/type both identified | 2 |
| Product or category/type identified | 1 | |
| Neither identified | 0 | |
| B. Function(s) | Any one function | 1 |
| No function | 0 | |
| C. Dangers or side effects and mitigation | One danger/side effect identified, explained and mitigated | 3 |
| Two of the three parts (see note below) | 2 | |
| Identified and explained, OR explained and mitigated | 1 | |
| No danger/side effect identified or mitigated | 0 | |
| D. Evaluation of products/processes | Evaluation using both similarities and differences | 2 |
| Evaluation using either similarities or differences | 1 | |
| No evaluation | 0 |
Note: In the source scheme, the 3-mark and 2-mark rows for part C use the same wording, which looks like a printing error. Ask your teacher how the 2-mark level is applied.
3. The learner appreciates the diversity and interactions of substances and their importance in life
Areas covered
How it is scored (maximum 9)
| Basis | Criteria | Score |
|---|---|---|
| A. Category with a reason | Category identified with a reason and an example | 3 |
| Category identified with either an example or a reason | 2 | |
| Category only, or reason only, or example only | 1 | |
| None | 0 | |
| B. Properties or predicted trends | At least four properties, characteristics or predictions | 3 |
| At least two | 2 | |
| Any one | 1 | |
| None | 0 | |
| C. Uses, applications or quantity (moles) | Any one use or application | 1 |
| None | 0 | |
| D. Environmental impact and mitigation | Impact and mitigation identified | 2 |
| Either impact or mitigation | 1 | |
| None | 0 |
4. The learner appreciates the existence of natural resources and their importance in daily life
Areas covered
How it is scored (maximum 9)
| Basis | Criteria | Score |
|---|---|---|
| A. Category, reason and example | Category with a reason and an example | 3 |
| Category with a reason OR with an example | 2 | |
| Category OR example only | 1 | |
| No category identified | 0 | |
| B. Composition | Any two components | 2 |
| Any one component | 1 | |
| No component | 0 | |
| C. Environmental impact, how it occurs, mitigation | One impact, how it occurs, and its mitigation | 3 |
| One impact with how it occurs, OR impact with mitigation | 2 | |
| One impact, OR how it occurs, OR its mitigation | 1 | |
| None | 0 | |
| D. Benefit or importance | Any one benefit | 1 |
| None | 0 |
5. Chemistry as a process of evidence-based enquiry
This is the biggest construct, worth 24 marks. It tests whether you can think and work like a scientist: plan an experiment, collect data, analyse it and conclude.
Assessable areas
The nine steps you will be scored on
| Step | Full marks need | Max |
|---|---|---|
| Aim | Aim with both key words (one key word earns 1) | 2 |
| Variables | Independent, dependent and controlled variables (two earn 2, one earns 1) | 3 |
| Hypothesis | Related to the experiment, with both key words (a wrong or missing hypothesis earns 0) | 2 |
| Procedure | Relevant materials, relevant procedure, and a coherent order | 3 |
| Risks and mitigation | One risk identified and mitigated (identified or mitigated only earns 1) | 2 |
| Presentation of data | 2/3 of the required data sets appropriately presented (1/3 earns 3; presented without the required sets earns 2; partial earns 1) | 4 |
| Recording of data | Appropriate recording within the error margin (partial within margin earns 3; outside margin earns 2 or 1; none or outside margin and unusable earns 0) | 4 |
| Data analysis and interpretation | A method that is appropriate and accurate (appropriate but partly accurate earns 2; appropriate but inaccurate earns 1) | 3 |
| Conclusion | A conclusion based on your data interpretation | 1 |
A worked example: rate of reaction
- Aim: To investigate how the concentration of an acid affects the rate of reaction with magnesium.
- Variables: Independent: acid concentration. Dependent: time taken or volume of gas produced. Controlled: temperature, mass of magnesium, acid volume.
- Hypothesis: The higher the acid concentration, the faster the rate of reaction.
- Risk and mitigation: Acid can irritate skin and eyes, so wear goggles and gloves.
- Recording and presentation: Record readings in a table with units, then plot a graph.
- Conclusion: State what the data shows and whether it supports the hypothesis.
Top tips to score full marks
- Use the scoring wording as a checklist. If a criterion says "identified, explained and mitigated", write all three, in that order.
- Give one thing fully rather than many things partly. Most criteria ask for "any one" danger or benefit, but done completely.
- Always add a reason and an example when you name a category.
- Record data with units and keep it within the expected error margin by measuring carefully.
- Mention safety in every practical: one risk plus how to reduce it earns the full 2 marks.
- Link your conclusion to your data. A conclusion with no data behind it earns nothing.
Frequently asked questions
What is an element of construct?
It is a statement of what a learner should appreciate or understand in a subject, such as "the learner appreciates the contribution of chemistry to our economy". Your assessment checks how well you demonstrate each one.
How many marks is each construct worth?
Based on the scoring tables: Construct 1 is 11, Construct 2 is 8, Construct 3 is 9, Construct 4 is 9, and Construct 5 is 24.
Do I need to cover every example listed under a construct?
You may be assessed on any of the listed areas, so be familiar with all of them. In an assessment you usually work on one product, process or resource and show the required parts in full.
Final word
The five constructs may look like a lot, but they reward the same habits: be specific, explain your reasoning, mention risks and benefits, and back your conclusions with evidence. Use the tables above as a checklist when you prepare, and you will know exactly where your marks come from.
The comparison with the old curriculum is based on public statements from UNEB, the Ministry of Education and Sports, and news reports. Elements of construct and scoring are based on the "Elements of Construct in the New Lower Secondary Curriculum" S4 Chemistry document (HeLP/2024/CHE/1). Scoring may be updated by UNEB or NCDC, so confirm details with your teacher.
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