WALA: WHY IS EVAPORATION IMPORTANT?

WALA: WHY IS EVAPORATION IMPORTANT?

L.O: to know that evaporation occurs when a liquid turns into a gas.

REVIEW THE PREVIOUS LESSON

•  Evaporation helps us to dry things such as washing, our hair, and food.

• Liquids evaporate faster when the air is moving.

STARTER

(Talk about it !)

• Why is it better to stay fully clothed in a hot desert, even if you feel very hot?

• It is better to stay fully dressed because this will slow down evaporation from the body. This means that the person won’t dehydrate as quickly. It will also prevent sunburn. 

ACTIVITY

( ALL STUDENTS )

Get cool faster

# Breathe onto the back of your hand. Does your breath feel warm or cool?

# Blow onto the back of your hand. Does it feel warmer or cooler than Your breath?

#Now put a drop of sanitizer on your hand and then blow on it. Blow gently and then blow harder. What do you feel ? 

OBSERVATION.

• Blowing on your hand feels cooler than your breath. Putting a drop of sanitizer and blowing on your hand feels cooler than just blowing. The reason for this is that any water/liquid on your hand uses heat energy from your body to evaporate. Blowing makes the water evaporate faster so that your hand feels cooler.

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QUESTIONS

1. Explain two ways in which a hairdryer makes water evaporate from our hair.

2. a). Think of three foods that are made by using evaporation.

b). Find more about how one of these foods is made.

3. Why do you think soil in the garden drles out more quickly on hot, wlndy days? 

CONCLUSION (answers)

1. It heats up the water in your hair which means that the water evaporates more quickly. It blows away the water vapour and speeds up evaporation in the same way that wind does.

2. Suggestions can include dried fruit, dried beans, dried milk,

b). Learners should be able to explain the drying process involved in making a food product they have named.

3. The heat from the Sun and the wind make water in the soil evaporate more quickly.