PSLE Science Glossary | Cycles, Systems, Interactions & Energy

PSLE Science keywords are useful only when pupils can connect the terms to observations, processes, diagrams and causal explanations. This glossary organises upper-primary Science vocabulary around cycles, systems, interactions, energy, matter and scientific reasoning so that a learner sees relationships rather than a flat list of definitions.

Parents searching for PSLE Science keywords, Primary 6 Science vocabulary, science command words or a Science glossary are usually trying to repair a language-content gap. A child may know what happened in an experiment but lack the precise vocabulary to explain it; another may know the term but use it as a label without describing the mechanism. Both need the same bridge: term → meaning → evidence → relationship → explanation.

For every item below, define it at the appropriate school level, identify an example and a non-example, and use it in a sentence that explains what changes or why. Use this page with the Singapore Vocabulary Guide and the eduKate Vocabulary Learning System.

Quick Read

Cycles, systems, interactions, energy, matter and reasoning.
Definition + example + non-example.
Connect vocabulary to diagrams and observations.
Use causal sentence frames.
Separate vocabulary gaps from Science misconceptions.

72 PSLE Science vocabulary items by theme

Cycles

1. cycle

For cycle, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

2. stage

For stage, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

3. sequence

For sequence, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

4. repeat

For repeat, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

5. evaporation

For evaporation, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

6. condensation

For condensation, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

7. precipitation

For precipitation, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

8. germination

For germination, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

9. reproduction

For reproduction, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

10. life cycle

For life cycle, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

11. water cycle

For water cycle, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

12. change of state

For change of state, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

Systems

13. system

For system, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

14. organ

For organ, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

15. function

For function, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

16. structure

For structure, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

17. transport

For transport, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

18. circulation

For circulation, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

19. respiration

For respiration, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

20. digestion

For digestion, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

21. absorb

For absorb, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

22. control

For control, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

23. coordinate

For coordinate, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

24. component

For component, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

Interactions

25. interaction

For interaction, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

26. force

For force, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

27. friction

For friction, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

28. gravity

For gravity, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

29. magnetism

For magnetism, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

30. push

For push, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

31. pull

For pull, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

32. effect

For effect, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

33. response

For response, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

34. adaptation

For adaptation, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

35. relationship

For relationship, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

36. dependence

For dependence, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

Energy

37. energy

For energy, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

38. heat

For heat, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

39. light

For light, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

40. electrical

For electrical, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

41. sound

For sound, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

42. transfer

For transfer, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

43. source

For source, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

44. conversion

For conversion, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

45. conductor

For conductor, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

46. insulator

For insulator, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

47. temperature

For temperature, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

48. movement

For movement, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

Matter and materials

49. matter

For matter, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

50. mass

For mass, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

51. volume

For volume, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

52. solid

For solid, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

53. liquid

For liquid, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

54. gas

For gas, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

55. property

For property, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

56. transparent

For transparent, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

57. opaque

For opaque, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

58. flexible

For flexible, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

59. waterproof

For waterproof, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

60. absorbent

For absorbent, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

Scientific reasoning

61. observe

For observe, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

62. infer

For infer, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

63. predict

For predict, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

64. compare

For compare, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

65. variable

For variable, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

66. evidence

For evidence, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

67. fair test

For fair test, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

68. conclusion

For conclusion, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

69. measurement

For measurement, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

70. pattern

For pattern, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

71. relationship

72. explain

For explain, write a subject-accurate definition, one clear example and one non-example. Then use it in an explanatory sentence that connects cause, observation or change. Finally, sketch or describe a diagram where the term would appear. This turns the word into usable Science language.

Science words need mechanism

Naming the correct term is often only the first layer. “Evaporation” identifies a process; a full explanation may need to connect temperature, liquid water, water vapour and the observed change. Build terms into causal relationships.

Choose three terms from different themes and apply this principle. Write one correct explanation, one incomplete explanation and one scientifically wrong explanation. Identify which vocabulary or reasoning link repairs each version.

Observation versus inference

Observation records what can be detected or measured; inference interprets what that evidence may mean. Pupils lose precision when they report an inference as though it were directly observed. Practise the pair side by side.

Structure and function

Many systems questions depend on the relationship between what something is like and what it allows the organism or object to do. Use frames such as “The structure ___ allows ___ because ___”. Vocabulary should make the mechanism visible.

Variables and fair tests

Scientific reasoning language controls experiment design. Identify what is changed, measured and kept the same. “Fair test” is not a decorative phrase; it describes a controlled comparison in which relevant factors are managed.

The Fencing Method

Fence close terms: heat/temperature, mass/volume, transparent/translucent/opaque where relevant, conductor/insulator, observation/inference. Put contrasting examples beside each other so the boundary becomes visible.

Diagrams and vocabulary

Labels should point to meaningful relationships, not float beside a picture. Ask pupils to speak a complete sentence from a diagram and then redraw a diagram from a sentence. This bidirectional translation strengthens subject language.

Command words

Science questions may ask pupils to state, describe, compare, predict, infer or explain. The same vocabulary can appear in different answer shapes. Underline the command before deciding how much reasoning to write.

Error diagnosis

If an answer is weak, decide whether the child lacks the term, misunderstands the concept, misses evidence, or cannot connect cause and effect in a sentence. The repair depends on the failure point.

30 glossary-to-explanation drills

Drill 1

Choose one term and define it without looking. Add an example, a non-example and one sentence using “because”, “therefore” or another causal link where appropriate. Then draw a simple diagram or observation table that would make the term meaningful in context.

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Frequently asked questions

Should pupils memorise definitions word for word?

Understanding matters more than exact repetition. The learner should explain accurately in clear language and apply the term.

How many keywords should be revised at once?

Use small conceptual groups and connect them with diagrams and examples.

Why do pupils use correct terms but still lose marks?

A label may be correct while the explanation lacks mechanism, evidence or the required comparison.

How should parents practise Science vocabulary?

Ask for example/non-example pairs and explanations from everyday observations.

How should teachers diagnose weak language?

Separate missing vocabulary from conceptual misconceptions and answer-structure problems.

Do diagrams help vocabulary?

Yes. Visual relationships create another route into meaning and retrieval.

Should pupils learn command words too?

Yes. They control what kind of response the content must become.

What shows mastery?

The pupil can move between term, explanation, observation, diagram and unfamiliar question.

Continue through the Singapore Vocabulary Guide.

eduKate SG

PSLE Science Glossary by Theme: Cycles, Systems, Interactions, Energy