S2.4.5 For the adult
Condensation
Why is the outside of a cold cup wet?
What this chapter teaches
Water vapour in the air turns into liquid drops when it touches something cold. This is condensation. The drops on a cold cup come from the air, not through the cup. Dew on grass is the same thing on a cool night.
Three questions to ask
There is no one right wording. Listen for the idea.
- Where do the drops on a cold cup come from?
- Why do you think drops do not appear on a warm cup?
- What does dew on grass have in common with the drops on a cold cup?
After the chapter, the learner can
- Explain why drops form on a cold cup or a pot lid
- Explain where the dew on grass comes from
What they copy into their notebook
Water vapour in the air touches something cold. It cools and turns into drops. This is condensation. It makes drops on a cold cup and dew on grass. The drops come from the air.