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Short answer. Most primary pupils who lose marks in Maths and Science are not missing whole topics. In Maths, the marks usually go on finding the wrong “whole” in fractions and percentage, treating ratio units as real values, misreading word problems, and copying a middle step as the final answer. In Science, they go on answers that say what happened without explaining why, everyday words where a science term is needed, and memorised answers that ignore the experiment in the question. Each has a specific fix, and none of them is “do more papers”.
This guide is written by Arché Academy’s primary tutors from what they see on P3 to P6 school papers in our Hougang classes. It covers the twelve places marks go in Maths, the twelve in Science, the science topics where misconceptions cost the most, and what a full-mark science answer looks like.
Why “more practice” often doesn’t fix it
When a child scores poorly in Maths, the usual response is more problem sums. When Science Booklet B goes badly, it is more model answers. Both can miss the point. A child who keeps failing problem sums may actually be unable to handle fractions, or may be misreading what the question asks. A child who scores poorly in Booklet B may know the content well and still not be able to apply it to an unfamiliar set-up, or structure an explanation.
The most useful thing a parent or tutor can do with a marked paper is to go through every wrong answer and ask why it was wrong, not just mark it wrong. Once the reason is clear, the fix usually is too.
Maths: where primary students lose marks
| Area | Common mistakes | How to avoid them |
|---|---|---|
| Basic calculations | Errors in addition, subtraction, multiplication and division; wrong regrouping | Practise number work, estimate the answer first, then check the calculation |
| Fractions | Wrong fraction operations; confusing a fraction of the remainder with a fraction of the total | Identify the correct whole before calculating |
| Ratio | Comparing the wrong quantities; treating ratio units as actual values; misunderstanding changing ratios | Set up the units clearly and use equivalent ratios or models |
| Percentage | Using the wrong base value; mixing up discount, increase, decrease and the original amount | Identify what represents 100% |
| Word problems | Misreading key words; missing information; misunderstanding what the question asks | Underline the key information, organise the relationships and state the unknown being asked for |
| Model drawing | Wrong model; unequal units; comparing the wrong quantities | Label each bar, unit and relationship clearly |
| Multi-step problems | Skipping steps; solving only part of the question; using an unsuitable strategy | Plan the steps before calculating and check each one against the question |
| Geometry | Misunderstanding angle properties, perimeter, area and volume; applying the wrong formula | Draw and label diagrams; revise properties and check units |
| Average | Confusing the total with the average; not accounting for a change in the number of items | Use Total = Average × Number of items |
| Units and conversion | Wrong conversions between cm and m, g and kg, mL and L, cm² and m², cm³ and m³ | Identify the unit required first and check conversions carefully |
| Data interpretation | Misreading graphs, scales, tables and intervals | Check the axes, labels and intervals before reading off values |
| Working and final answers | Missing essential working; wrong units; copying a middle step as the final answer | Show the steps in order and clearly mark the final answer |
Example: the “wrong whole” in fractions
Mei had $120. She spent 1/4 of it on a book and 1/3 of the remainder on a bag. How much did she have left?
The common wrong answer adds 1/4 and 1/3 to get 7/12 spent, then works out 5/12 of $120 = $50. The mistake is treating “1/3 of the remainder” as 1/3 of the $120.
The right working finds the remainder first. After the book, 3/4 of $120 = $90 is left. The bag costs 1/3 of $90 = $30. She has $90 − $30 = $60 left.
The child who wrote $50 knows how to add fractions. What went wrong is the whole, and more fraction drills won’t fix that. Asking “a fraction of what?” before every calculation will. Our step-by-step method for PSLE problem sums builds that habit, and this guide to non-routine questions covers choosing the right strategy.
Science: where primary students lose marks
| Area | Common mistakes | How to avoid them |
|---|---|---|
| Content knowledge | Forgetting facts, definitions, functions and processes | Revise key concepts and test recall regularly |
| Scientific keywords | Using vague everyday language instead of accurate science terms | Learn the keywords and understand when to use them |
| Conceptual understanding | Memorising model answers without understanding why something happens | Explain each process as cause and effect |
| Application questions | Not recognising the concept being tested in an unfamiliar situation | Look for clues in the diagram, the experiment and the question |
| Incomplete explanations | Stating what happened without explaining why | Link the science concept to the observation and the result |
| Comparison questions | Explaining only one object or condition instead of comparing both | Use comparing words: greater, less, faster, slower |
| Experimental questions | Confusing variables, reliability, accuracy and fair testing | Identify what is changed, what is measured and what is kept the same |
| Graphs and tables | Reading values wrongly or drawing conclusions the data doesn’t support | Quote the relevant values and describe the actual trend |
| Scientific terms | Confusing evaporation with condensation, heat with temperature, mass with weight | Revise common misconceptions and definitions |
| Predictions | Predicting without a scientific reason | Back the prediction with the evidence and the science concept |
| Multiple-choice questions | Choosing an option because of a familiar keyword rather than checking every statement | Check each option against the information given and the science |
| Answer relevance | Giving a memorised explanation that doesn’t address the specific question | Identify the command word and what the answer must show before writing |
Science topics where misconceptions cost the most marks
| Topic | Common mistakes and misconceptions |
|---|---|
| Heat and temperature | Saying an object “gains temperature” instead of gains heat; confusing heat transfer with temperature change; assuming all objects expand equally |
| Evaporation and condensation | Confusing the two; not identifying where the water vapour came from; leaving out the gain or loss of heat |
| Light and shadows | Not understanding how light travels; confusing shadow size with object size; wrong reasoning about distance from the light source |
| Electricity | Confusing open and closed circuits; misunderstanding series and parallel; thinking bulbs “use up” current |
| Magnetism | Thinking attraction proves an object is a magnet; confusing magnetic materials with magnets; misunderstanding repulsion |
| Forces | Confusing mass with weight; misunderstanding friction; not identifying all the forces acting on an object |
| Plant transport system | Confusing xylem and phloem; misunderstanding how water, mineral salts and food are carried |
| Photosynthesis | Confusing making food with taking in water; getting the raw materials and products wrong |
| Respiratory and circulatory systems | Confusing breathing with respiration; leaving out the role of oxygen, blood and energy release |
| Digestive system | Confusing digestion with absorption; naming the wrong place where nutrients are absorbed |
| Reproduction | Confusing pollination with fertilisation; mixing up the functions of flower parts |
| Life cycles | Getting the stages in the wrong order; confusing complete and incomplete metamorphosis |
| Adaptations | Describing a structural or behavioural feature without explaining how it helps the organism survive |
| Interactions and environment | Misreading food chains; confusing the flow of energy with the movement of organisms; overlooking how organisms depend on each other |
Magnetism is the one we see most often in P3 and P4. “The nail is attracted to the magnet, so the nail is a magnet” loses the mark. Attraction only shows the nail is made of a magnetic material. Only repulsion proves an object is a magnet.
PSLE science answering techniques: two before-and-after answers
1. Missing scientific keywords
Weak answer: “The water disappeared because it was hot.”
Improved answer: “The water gained heat from the surroundings and evaporated to form water vapour.”
The improved answer names the process (evaporation), explains the heat transfer (gained heat from the surroundings) and says what happened to the water (it became water vapour). The weak answer has none of the three, so it scores nothing even though the child probably understood what happened.
2. A result without a complete explanation
Question: Why does the heart beat faster during exercise?
Weak answer: “To provide more oxygen.”
Improved answer: “The heart pumps faster to transport oxygen and digested food to the body cells at a faster rate for respiration, so that energy is released at a faster rate to sustain the physical activity.”
The weak answer is not wrong, but it stops halfway. The improved answer follows the chain all the way: what the heart does, what the blood carries, where it goes, why the cells need it, and what that does for the activity. Open-ended Booklet B questions are usually marked on that chain, so every missing link is a lost mark.
How to use this at home
Take your child’s last marked paper and go through only the wrong answers. For each one, ask which row in the tables above it belongs to. You do not need to be a tutor to do this. You only need to ask “what made this wrong?” instead of “what is the right answer?”
Two or three rows usually stand out. If most lost marks are in word problems, working and final answers, or incomplete explanations, the problem is habit and technique, and it can improve within a term. If they are in fractions, ratio or content knowledge, there is a content gap to close first, before more exam practice will help.
How our tutors work through it
In class we follow the same order every time a child joins:
- Diagnostic assessment: a marked paper or a short test to see where marks are going.
- Error classification: every wrong answer sorted by its underlying reason, using the areas above.
- Foundational revision: the content gaps closed first.
- Application practice: unfamiliar questions on the same concepts.
- Timed assessment: the same skills under exam conditions.
- Progress review: back to step 1 with the next paper.
The aim is to find the root cause of the lost marks and fix it, rather than drilling exam papers while the same mistake repeats.
Bring the last marked paper to a trial lesson
We teach P3 and P4 Maths and Science together in one class, and PSLE Maths and Science for P5 and P6, five students at most, at our Hougang centre near Kovan MRT. The tutor will go through where the marks went and tell you what needs fixing first.
Primary maths tuition · Primary science tuition · Book a trial lesson →
Frequently Asked Questions
Where do students lose the most marks in PSLE Maths?
Commonly on fractions and percentage (using the wrong whole or base), ratio (treating units as actual values), word problems (misreading what is asked), multi-step problems (solving only part of the question) and working (copying a middle step as the final answer). Most of these are habits rather than missing topics.
Why does my child know the science content but still lose marks in Booklet B?
Booklet B marks the explanation, not just the fact. The usual reasons are answers that state what happened without explaining why, everyday words instead of science terms, and memorised answers that don’t refer to the experiment or set-up in the question.
What are the most important PSLE science answering techniques?
Use the correct science keyword, link the concept to the observation and the result, compare both conditions when a question asks you to compare, and read the command word before writing so the answer addresses that specific question.
Which science topics have the most misconceptions?
Heat and temperature, evaporation and condensation, magnetism, electrical circuits, breathing versus respiration, digestion versus absorption, and pollination versus fertilisation are among the most common.
Are careless mistakes in Maths really careless?
Often not. A repeated “careless” mistake usually has a cause: a method still held together by memory, a habit of not labelling models, or skipping the check against the question. Sorting the mistakes by type shows whether it is carelessness or a gap.
How can I find out why my child is losing marks?
Go through every wrong answer on the last marked paper and decide which area each one belongs to, using the tables in this guide. If two or three areas account for most of the lost marks, that is where to focus.
For what the scores mean once the marks are in, try our PSLE score calculator. If your child is in P4, the guide to Standard and Foundation subjects explains the decision coming up after the year-end exams.