Quick Read: Primary Science answers are often lost not because the student knows nothing, but because the scientific relationship is expressed vaguely. Strong Science language connects evidence → concept → mechanism → conclusion. Vocabulary matters when it makes the explanation more exact.
This legacy page keeps its original title and URL. The 2026 library edition serves search intent around Primary Science vocabulary, PSLE Science open-ended answers, scientific vocabulary, Science answer techniques, cause and effect in Science and how to answer Science questions. The page is written as a reference guide rather than a timetable or class advertisement.
Scientific Vocabulary Is Part of Understanding
A keyword by itself is not an explanation. Writing evaporation, friction or photosynthesis does not automatically show that the student understands what is happening. The word must be connected to the observation and the mechanism.
Compare: “The water disappeared because of evaporation.” That may be partly correct, but a stronger answer identifies what changed and why: “Water at the surface gained enough energy to change from liquid water into water vapour, so the amount of liquid water decreased.”
The Four-Layer Science Answer
- Evidence: What does the question, table, diagram or observation show?
- Concept: Which scientific idea applies?
- Mechanism: What process or relationship explains the change?
- Conclusion: What directly answers the question?
Common Science Language Jobs
| Language job | Useful words and structures |
|---|---|
| Compare | greater than, lower than, more, less, similar, different |
| Cause | because, due to, causes, results in, leads to |
| Sequence | first, then, subsequently, eventually |
| Change | increase, decrease, remain constant, fluctuate, accelerate |
| Evidence | shows, indicates, supports, suggests |
| Condition | if, when, provided that, under these conditions |
| Function | allows, enables, prevents, reduces, transfers |
| Uncertainty | may, could, likely, suggests rather than proves |
Observation Is Not the Same as Explanation
Students often repeat the data instead of explaining it. If a plant in bright light grows faster than a plant in dim light, repeating “the plant in bright light grew faster” is observation. The explanation must connect the condition to the relevant process.
| Layer | Example |
|---|---|
| Observation | Plant A increased in height more than Plant B. |
| Concept | Light is needed for photosynthesis. |
| Mechanism | More suitable light conditions can support greater food production for growth. |
| Conclusion | This helps explain why Plant A showed more growth under the stated conditions. |
Use Scientific Terms Only When They Fit
A student may remember a keyword from revision and insert it whenever the topic appears. That creates wrong answers. For example, not every movement of water in plants should be labelled transpiration; transpiration specifically concerns water vapour loss from aerial parts, especially through stomata. Precision requires knowing the boundary of the term.
Primary Science Vocabulary by Function
Processes
- evaporation
- condensation
- melting
- freezing
- photosynthesis
- respiration
- pollination
- germination
- decomposition
Relationships
- cause
- effect
- increase
- decrease
- transfer
- absorb
- release
- conduct
- insulate
Evidence and investigation
- observe
- measure
- variable
- fair test
- comparison
- result
- conclusion
- repeatability
Systems and structures
- function
- organ
- structure
- adaptation
- circuit
- component
- habitat
- food chain
Command Words Change the Answer
| Command | What the student should do |
|---|---|
| State | Give the required fact or result directly. |
| Describe | Say what happens or what the pattern looks like. |
| Explain | Give the reason or mechanism. |
| Compare | State a meaningful similarity or difference using both items. |
| Predict | Use known patterns or mechanisms to say what is likely to happen. |
| Suggest | Offer a scientifically plausible explanation or method from the available evidence. |
Vague Words That Need Repair
| Vague answer | More precise direction |
|---|---|
| It changed. | State what increased, decreased or transformed. |
| It helps the plant. | State which process or function is supported. |
| It has more energy. | Specify what type of energy and what evidence supports the claim. |
| The object is stronger. | State stronger in what sense: harder to break, supports more load, resists bending? |
| The animal adapted. | Name the feature and how it helps survival or reproduction. |
| The experiment is fair. | State which variable was changed and which were kept the same. |
Cause-and-Effect Chains
Many open-ended answers become clearer when written as a chain rather than one jump.
Condition → process → immediate effect → final observation.
Example: “The metal spoon is a good conductor of heat → thermal energy is transferred through the spoon more quickly → the handle becomes hotter sooner.”
Comparisons Need Two Sides
If asked to compare A and B, an answer that mentions only A may be incomplete. Use paired language: “A has a greater surface area than B”, “A took less time than B”, or “Both increased, but A increased more rapidly.”
Graphs and Tables: Read Before Explaining
- Identify what each axis, row or column represents.
- State the trend without explaining it yet.
- Notice exceptions or plateaus.
- Only then connect the pattern to a scientific mechanism.
This separation prevents students from inventing explanations before they have read the evidence correctly.
Variables in Investigation Questions
| Variable type | Question |
|---|---|
| Changed variable | What did the experimenter deliberately change? |
| Measured variable | What result was observed or measured? |
| Controlled variables | What conditions were kept the same to make the comparison meaningful? |
Students should use the language of the actual experiment rather than memorising generic phrases such as “keep everything the same”.
Model Answers: Use Them as Structures, Not Scripts
A model answer can show a good chain of reasoning, but memorising its exact wording creates dependence. Change the surface details and ask the learner to rebuild the explanation from the underlying mechanism.
For example, after learning one heat-transfer explanation, vary the material, thickness, starting temperature or measurement. If the student still explains correctly, the knowledge is transferable.
Primary 3–4: Build the Language of Observation and Cause
At earlier Primary Science levels, students need secure vocabulary for classification, life cycles, materials, magnets, light, heat and basic investigations. The main language goal is to connect clear observation with simple cause-and-effect statements.
Primary 5–6: Integrate Systems and Evidence
Upper Primary questions increasingly require several ideas at once. A student may have to read a diagram, compare two conditions, identify a mechanism and explain the outcome. Vocabulary, knowledge and reasoning must coordinate.
A Science Error Log
| Error type | Example |
|---|---|
| Missing concept | Answer describes the result but never names the relevant idea. |
| Wrong mechanism | Correct topic, incorrect causal explanation. |
| Vocabulary misuse | Keyword used outside its scientific meaning. |
| Incomplete comparison | Only one item discussed. |
| Evidence ignored | Answer contradicts table, graph or diagram. |
| Question misread | Student explains when asked only to state, or vice versa. |
| Over-generalisation | Claim is broader than the evidence allows. |
A 15-Minute Open-Ended Repair Routine
- Choose one previously wrong question.
- Highlight the evidence in the question.
- State the concept in one phrase.
- Write the mechanism as a cause-and-effect chain.
- Answer the question directly in one or two complete sentences.
- Compare with the model answer for missing relationships, not identical wording.
- Repeat a similar question after a delay.
Frequently Asked Questions
Do Science answers need special keywords?
Scientific terms matter, but they must be used accurately inside a complete explanation. Keywords are not magic marks.
Should answers be long?
Not necessarily. A concise answer that contains the correct relationship is better than a long answer full of irrelevant statements.
Why do students lose marks even when they know the topic?
Because knowing a concept and representing it precisely under question constraints are different skills. Diagnosis should identify whether the gap is knowledge, reasoning, language or question reading.
Library Routes
- Singapore Learning Library
- Science Article Directory
- Science is FUN! – Transportation of Water in Plants
Library note: The original 2017 page was a short tuition note about scientific vocabulary. The 2026 edition preserves its title and URL while rebuilding it as a Primary Science language-and-reasoning reference focused on evidence, mechanisms, command words, variables, answer precision and error diagnosis.