Liquid water can become water vapour through evaporation, and water vapour can become liquid water through condensation. The names become easier to remember when the learner follows the starting state, ending state and direction of heat transfer.
For families exploring schools in Yishun, this guide connects verified local science context with independent written scenarios. It does not require heating water, handling ice or setting up equipment.
Compare a drying wet surface with droplets forming on a sufficiently cold surface. Explain where the water comes from instead of saying it has simply disappeared or passed through a container.
eduKateSG · Neighbourhood education
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1 · Local context · 2 · Worked example · 3 · Family practice
Contents
Explore, practise and connect · Four chapters
CHAPTER 1 OF 4
1. Connect local science with explaining a process
Yishun Primary School’s Science page describes inquiry and experiences connecting concepts to everyday contexts. Its science-kit section includes terrariums used to observe the water cycle.
The scenarios below are independently written by eduKateSG, not Yishun Primary experiments or reports of pupil observations. The source provides local context rather than a claim that the school teaches these exact examples.
Before naming a process, ask what the water was like before and after. A change of state is different from water moving from one place to another while remaining liquid.
CHAPTER 2 OF 4
2. Explain evaporation without requiring boiling
Imagine a small amount of water spread on a surface, with no spill or wiping, gradually becoming less visible as water enters the surrounding air. Evaporation changes liquid water at the surface into water vapour.
Evaporation can occur below water’s boiling point. A wet surface does not need to reach boiling temperature to dry. Avoid using boiling and evaporation as interchangeable labels.
Energy is needed for evaporation. The water can take in energy from its surroundings as evaporation continues. The resulting water vapour is an invisible gas.
The water has not ceased to exist simply because the wet patch becomes smaller. A useful explanation tracks it from liquid on the surface to water vapour in the air.
CHAPTER 3 OF 4
3. Explain condensation and the source of droplets
Now imagine humid air contacting the outside of a sealed, leak-free container whose surface is sufficiently cold. Water vapour from the air can condense into droplets on that outside surface.
In this scenario, the droplets do not have to come through the container wall. The water vapour was already present in the surrounding air before becoming liquid.
During condensation, water vapour loses heat and changes into liquid water. The explanation identifies both the state change and the relevant cooling, rather than saying coldness creates water.
A visible mist consists of tiny liquid droplets, not the invisible water vapour itself. This distinction helps when a learner describes a cloud-like appearance near cooling water vapour.
CHAPTER 4 OF 4
4. Compare the two changes carefully
Ask the child to complete two state descriptions: evaporation is liquid to gas; condensation is gas to liquid. Then connect evaporation with gaining energy and condensation with losing heat.
Return to the sealed-container scenario and ask where the outside water originated. A suitable answer names water vapour in the surrounding air, under the stated conditions.
If a real container might be leaking or splashed, the appearance of droplets alone would not settle their source. This written example rules out those alternatives; an actual investigation would need to consider them.
Finish with a short explanation that names the process, states and heat transfer. Following the water makes the idea clearer than memorising two labels without knowing what each describes.
Sources and scope
School information checked on 16 October 2026 (Singapore time): Yishun Primary School Science. Programmes may change. Family activities are independently written by eduKateSG, not official school tasks. This article does not imply school endorsement, rank schools or guarantee admission or learning results.