PSLE Science vocabulary is the language of mechanisms, evidence and accurate explanations. A Primary 6 student might remember that water droplets appear on a cold cup but still write the wrong cause if they confuse condensation with evaporation. This guide gives 200 words and scientific terms, each with a simple definition, selected to help Singapore learners connect knowledge with open-ended answers.

The current MOE Primary Science syllabus is organised around Diversity, Cycles, Systems, Energy and Interactions. The 2026 PSLE Science standard-subject code is 0009. Vocabulary is useful only when students can explain the processes, control the variables, interpret observations and apply ideas to unfamiliar situations. This is an eduKate teaching list, not an officially mandated collection of 200 examination words.

Start here:

• Practise inquiry words first: observation, inference, evidence and fair test.
• Learn scientific processes as cause → change → outcome, not isolated definitions.
• Pay special attention to confusing pairs: pollination/fertilisation, evaporation/boiling, heat/temperature.
• Use diagrams, household observations and simple safe activities; avoid rote copying.
• Some entries extend useful knowledge beyond the basic Primary learning outcomes; follow the child’s school topics for examination priorities.

1–10: Scientific inquiry and fair tests

1. observation — Information collected directly through senses or instruments.
2. inference — An explanation or interpretation based on observations.
3. hypothesis — A testable suggested explanation.
4. prediction — A reasoned statement about what may happen.
5. variable — A factor that may change in an investigation.
6. changed variable — The factor deliberately varied for a fair test.
7. measured variable — The factor observed or measured as the result.
8. controlled variable — A factor kept the same for a fair comparison.
9. fair test — An investigation designed to compare effects without unfair changes.
10. evidence — Observations or data used to support a claim.

11–20: Investigations and recording

11. apparatus — Equipment used in an experiment.
12. procedure — A sequence of steps used to carry out a test.
13. trial — One attempt or run of an experiment.
14. repeat — Carry out a test again.
15. reliability — How dependably a result is obtained under suitable repeated conditions.
16. accuracy — How close a measurement is to the true value.
17. measurement — A value found using an appropriate instrument and unit.
18. data — Recorded observations or numbers.
19. result — What an experiment reveals or measures.
20. control setup — A comparison arrangement without the tested change.

21–30: Diversity and classifying things

21. organism — An individual living thing.
22. living thing — Something showing life processes.
23. non-living thing — Something that does not perform life processes.
24. classification — Sorting objects or organisms using shared characteristics.
25. characteristic — A distinguishing feature.
26. diversity — Variety among living things or materials.
27. habitat — The natural place where an organism lives.
28. adaptation — A feature or behaviour that helps survival in an environment.
29. species — A group of organisms defined by shared biological characteristics.
30. biodiversity — The variety of living things in a place.

31–40: Flowering plant structures

31. root — Plant part commonly anchoring it and absorbing water.
32. stem — Plant part supporting leaves and transporting materials.
33. leaf — Plant structure that usually makes food by photosynthesis.
34. flower — Plant reproductive structure in flowering plants.
35. petal — Often colourful flower part that may attract pollinators.
36. stamen — The male reproductive part of a flower.
37. pistil — The female reproductive structure of a flower.
38. ovary — The flower part containing ovules.
39. anther — The stamen part that produces pollen grains.
40. stigma — The receptive surface on which pollen can land.

41–50: Plant life cycles and reproduction

41. seed — Structure containing a young plant and stored resources.
42. germination — When a seed begins developing into a seedling.
43. seedling — A young plant that has started growing.
44. pollination — Transfer of pollen to a compatible stigma.
45. fertilisation — Fusion of reproductive cells leading to seed development.
46. dispersal — Movement of seeds away from the parent plant.
47. embryo — A young developing organism within a seed or egg.
48. fruit — The mature ovary that usually contains seeds.
49. offspring — The young produced by living things.
50. reproduction — Producing new living organisms.

51–60: Animal groups and life cycles

51. egg — A reproductive structure from which a young animal may develop.
52. larva — An immature stage unlike the adult in some animals.
53. pupa — An intermediate stage in complete insect metamorphosis.
54. adult — A mature stage of an animal’s life.
55. metamorphosis — A major change of body form during development.
56. life cycle — The sequence of stages through an organism’s life.
57. mammal — An animal group whose mothers produce milk for young.
58. bird — A feathered vertebrate animal.
59. insect — An arthropod with six legs in the adult stage.
60. amphibian — A vertebrate group often with aquatic and land life stages.

61–70: Human digestion and circulation

61. digestion — Breaking down food into smaller absorbable substances.
62. absorption — Movement of digested nutrients into the body.
63. nutrient — A useful substance obtained from food.
64. stomach — Organ that churns food and helps chemical digestion.
65. intestine — Part of the digestive tract where nutrients are absorbed.
66. lungs — Organs where gases are exchanged with the blood.
67. heart — Muscular organ that pumps blood around the body.
68. blood — Fluid carrying materials such as oxygen and nutrients.
69. oxygen — Gas needed by most human cells for respiration.
70. carbon dioxide — Gas released during respiration and used in photosynthesis.

71–80: Plant systems and making food

71. photosynthesis — Process by which green plants use light to make food.
72. chlorophyll — Green pigment that absorbs light used in photosynthesis.
73. chloroplast — Plant cell structure where photosynthesis takes place.
74. stomata — Tiny pores allowing gas exchange in many leaves.
75. transport — Movement of materials from one part to another.
76. water uptake — Absorption of water, often by roots.
77. food production — Making sugars using raw materials and energy.
78. respiration — Process releasing usable energy from food in living cells.
79. gas exchange — Movement of gases into and out of an organism.
80. circulation — Movement of substances around a body or system.

81–90: Ecosystems and feeding relationships

81. ecosystem — Living organisms and their non-living environment interacting.
82. population — Organisms of one species in the same area.
83. community — Different living populations in an area.
84. producer — Organism, usually a green plant, making its own food.
85. consumer — Organism obtaining food from other organisms.
86. predator — Animal that hunts and eats another animal.
87. prey — Animal hunted and eaten by a predator.
88. food chain — A sequence showing feeding relationships and energy transfer.
89. food web — Several interconnected food chains.
90. energy flow — Movement of energy through a feeding relationship.

91–100: Interactions in living environments

91. competition — Organisms seeking the same limited resource.
92. interdependence — Organisms depending on one another.
93. parasitism — Relationship in which one organism benefits at another’s expense.
94. symbiosis — Close biological interaction between different organisms.
95. camouflage — Colouring or shape that makes an organism difficult to notice.
96. mimicry — Resembling something else to gain an advantage.
97. environmental factor — A condition affecting organisms in a habitat.
98. scarcity — A shortage of a needed resource.
99. survival — Remaining alive in an environment.
100. extinction — Permanent loss of every member of a species.

101–110: Matter and changes of state

101. matter — Anything that has mass and occupies space.
102. mass — A measure of the quantity of matter.
103. volume — Amount of space occupied.
104. solid — A state of matter with fixed shape and volume.
105. liquid — A state with fixed volume but not fixed shape.
106. gas — A state that spreads to fill its container.
107. particle — A tiny unit used to model matter.
108. melting — Changing from solid to liquid.
109. freezing — Changing from liquid to solid.
110. boiling — Rapid vaporisation within a liquid at its boiling point.

111–120: Water movement and the water cycle

111. evaporation — Liquid changing to gas from its surface.
112. condensation — Gas changing to liquid.
113. precipitation — Water falling from clouds as rain or other forms.
114. water vapour — Water in its gaseous state.
115. water cycle — Continuous movement of water through the environment.
116. runoff — Water flowing over the land surface.
117. collection — Water gathering in bodies such as rivers and seas.
118. surface — The outer boundary of a substance or object.
119. humidity — Amount of water vapour in the air.
120. cloud — A visible mass of tiny water droplets or ice crystals.

121–130: Light and shadows

121. light — Energy that enables vision and travels in rays.
122. reflection — Light bouncing off a surface.
123. shadow — A dark area formed when light is blocked.
124. transparent — Allows light through so objects are seen clearly.
125. translucent — Allows light through but scatters it.
126. opaque — Does not let light pass through.
127. luminous — Producing light of one’s own.
128. light source — An object that emits light.
129. ray — A straight line used to show light direction.
130. beam — A collection of light rays travelling together.

131–140: Heat and temperature

131. heat — Energy transferred because of a temperature difference.
132. temperature — A measure of how hot or cold something is.
133. conduction — Transfer of thermal energy through material contact.
134. thermal conductor — Material that transfers heat relatively readily.
135. thermal insulator — Material that slows transfer of heat.
136. expansion — Increase in size, sometimes due to heating.
137. contraction — Decrease in size, sometimes due to cooling.
138. thermometer — Instrument that measures temperature.
139. heat transfer — Movement of thermal energy between places or objects.
140. temperature difference — The condition that drives heat transfer.

141–150: Electrical systems and circuits

141. circuit — A connected path along which electric current can flow.
142. electrical cell — A source supplying electrical energy to a circuit.
143. battery — One or more connected electrical cells.
144. bulb — A device that converts electrical energy to light and heat.
145. switch — A component used to open or close a circuit.
146. wire — Material pathway connecting circuit components.
147. electrical conductor — Material allowing electric current to flow readily.
148. electrical insulator — Material resisting electric current flow.
149. closed circuit — A complete path that allows current to flow.
150. open circuit — A broken or incomplete path preventing current.

151–160: Forces, magnets and motion

151. force — A push or pull that can change motion or shape.
152. gravity — Attractive force between masses, felt as weight near Earth.
153. friction — Force resisting relative motion between touching surfaces.
154. magnetism — Physical effects associated with magnets and magnetic fields.
155. magnet — An object producing a magnetic field.
156. north pole — One end of a magnet, with characteristic interactions.
157. south pole — The other end of a magnet.
158. attraction — A pulling-together interaction.
159. repulsion — A pushing-apart interaction.
160. elastic force — Force produced when an elastic object is stretched or compressed.

161–170: Energy forms and conversions

161. energy — The capacity for causing change or doing work.
162. energy conversion — Change from one form of energy to another.
163. electrical energy — Energy associated with moving or stored electric charge.
164. light energy — Energy carried by visible electromagnetic radiation.
165. sound energy — Energy carried by vibrations through a medium.
166. heat energy — Everyday school term for thermal energy transferred or stored.
167. chemical energy — Energy associated with chemical substances and reactions.
168. kinetic energy — Energy associated with motion; useful secondary bridge.
169. stored energy — Energy available for a later change or transfer.
170. energy source — Something providing energy to a system.

171–180: Microorganisms and everyday health

171. microorganism — A microscopic organism, such as many bacteria and fungi.
172. bacterium — A single-celled microorganism of the bacterial group.
173. fungus — Organism such as yeast or mould that absorbs nutrients.
174. mould — A type of fungus that can grow on damp material.
175. yeast — A single-celled fungus used in some food processes.
176. virus — Infectious agent that reproduces only inside suitable living cells.
177. infection — Entry and multiplication of disease-causing agents in a host.
178. hygiene — Practices that help prevent illness and contamination.
179. decomposition — Breaking down dead material into simpler substances.
180. spoilage — Undesirable changes that make food or materials unusable.

181–190: Environment and decisions

181. pollution — Harmful contamination of air, land or water.
182. conservation — Protection and careful use of natural resources.
183. recycling — Processing used material into new products.
184. renewable resource — A resource replenished naturally on a useful time scale.
185. non-renewable resource — A resource not replaced quickly enough for continued use.
186. climate — Long-term patterns in weather conditions.
187. resource — Something useful that people or organisms can draw upon.
188. sustainability — Meeting needs while protecting conditions for the future.
189. waste — Material no longer wanted for its current use.
190. environmental protection — Actions reducing harm to nature and habitats.

191–200: Science questions and command words

191. describe — Say what happens or what is observed.
192. explain — Give the scientific reason or mechanism.
193. compare — Describe important similarities and differences.
194. contrast — Focus on differences between two situations.
195. suggest — Offer a plausible idea supported by knowledge.
196. justify — Support an answer with sound evidence or reasons.
197. deduce — Reach a conclusion logically from supplied information.
198. state — Give a concise answer without extra explanation unless asked.
199. identify — Name or select the requested thing.
200. evaluate — Judge strengths, weaknesses or quality using evidence.

What good scientific vocabulary does inside an actual answer

Example 1: Water droplets on a cold bottle

A bottle comes out of a refrigerator. Water droplets form on the outside. The scientific process is condensation: water vapour in the surrounding air loses thermal energy when cooled and changes into liquid water on the cool surface. The droplets did not pass through an ordinary intact bottle. The important language is: source of water vapour → cooling → change of state → observation. Compare this with our cold-cup condensation explanation.

Example 2: Pollination does not mean fertilisation

Pollination is the movement of pollen to a compatible stigma. Fertilisation takes place later when reproductive cells fuse. Seed dispersal comes after seeds develop, while germination describes a seed beginning to grow in suitable conditions. If a child combines these distinct stages into one word, the answer loses its sequence and causal logic.

Example 3: What makes a fair test fair?

Two similar cups contain equal volumes of hot water at the same starting temperature. One cup has a lid and one does not. The lid is the changed variable; the temperature after ten minutes is the measured variable. Cup material, room conditions, water quantity and starting temperature should be held the same where possible. The result may show a difference, but the explanation still has to use evidence rather than guesswork.

Example 4: An electrical circuit must be complete

A bulb lights when its circuit provides a complete conducting path and suitable power source. “The battery sends electricity” is often too vague. Better: “Closing the switch completes the circuit, allowing electric current to flow through the bulb.” In real school practical work, the exact observation and circuit arrangement determine the most accurate answer.

Example 5: A food chain is a relationship, not a random list

Grass → grasshopper → frog describes who eats whom and the direction energy is transferred. A producer makes food; a consumer obtains energy by feeding on other organisms. Not every organism in a diagram belongs to one simple chain: several linked chains form a food web. When a population changes, the effect on other organisms depends on the relationships shown.

The three-part answer pattern

A good open-ended answer often follows observation → scientific concept → causal explanation. For example, “The covered container cooled more slowly” is an observation; “The lid reduces some heat transfer and evaporation” is a scientific explanation. Avoid adding a concept that the setup does not support. If the graph is unclear, quote the relevant values before drawing a conclusion. Read why data should come before a Science conclusion.

A four-week vocabulary-and-concept plan

1. Week 1 — Inquiry and Diversity: group investigation terms with classification and plant/animal structures. Draw, label and explain examples.
2. Week 2 — Cycles and Systems: trace life cycles, water changes, digestion and plant transport using arrows and cause-effect sentences.
3. Week 3 — Energy and Interactions: practise circuits, heat, light, forces and ecosystems with diagrams or everyday observations.
4. Week 4 — Evidence and transfer: answer unseen application questions, compare your response with the actual data, revise incorrect causal words and retry independently.

Parent’s checklist: does the child understand or only recognise?

• Can the child define a term simply without copying textbook wording?
• Can they show the process as a labelled diagram or a sequence?
• Can they explain a counterexample, such as why evaporation can happen without boiling?
• Can they identify the measured and changed variables in a new fair-test setup?
• Can they use the word in a clear sentence that answers the exact question?

Frequently asked questions

Are all 200 words officially examinable?

No. This is an editorial glossary covering the curriculum’s core ideas plus a few connecting and extension terms. The official MOE teaching syllabus and current SEAB assessment documentation determine examination coverage.

Should children memorise definitions word for word?

Understanding the mechanism and using precise scientific language matter more. Some definitions have required elements, but a child should be able to explain why each element is present.

What is the difference between an observation and an inference?

“The metal strip became longer” reports an observation. “The strip expanded because it was heated” draws an inference and provides a possible scientific explanation.

Is scientific vocabulary the same as difficult English?

No. Often the key is selecting a simple exact word, such as absorb rather than drink or melt rather than disappear.

How does vocabulary connect to PSLE open-ended questions?

It lets the child name the process, describe the relationships and avoid contradicting the evidence in the question.

How can families practise in Punggol?

Use everyday surroundings to ask safe observation questions: shadows under a shelter, water droplets on a bottle, plant parts along a walkway or the effect of a magnet on different household items. Do not collect or disturb wildlife, and do not carry out unsafe electrical experiments.

Official references and related eduKate articles

MOE’s Primary Science Teaching and Learning Syllabus (2023 cohort; May 2024 update) describes the five major themes and how skills build from P3 to P6. SEAB’s 2026 PSLE subject and format index lists standard Science as 0009 and Foundation Science separately as 0039. For an application-focused continuation, use Science Is an Evidence Language and P5–P6 and PSLE Science revision in Punggol. Always check the current examination year’s official instructions before planning assessment preparation.

eduKate Punggol, November 2026. This glossary supports scientific thinking rather than replacing the MOE syllabus or a student’s school materials.