Water Cycle in a Bag
Evaporation, condensation, and precipitation
What you need:
- A sealable sandwich bag
- Blue food colouring
- A permanent marker
- Sticky tape
- A teaspoon
1. Put some water in a container and add a teaspoon of blue food colouring.
2. Mix well.
3. Take the sealable sandwich bag and draw a sun, some clouds, sea and a bit of land with trees etc. — you can colour the sun and the land and trees if you want to)
4. Pour the blue water into the bag and seal it.
5. Stick the bag on a sunny window using the tape.
6. Leave the bag on the window for a while and observe what happens when the sun starts to heat up the water.
You can take pictures of the bag so you can record your findings (this is very important for young scientists)
The science behind it:
When the water gets heated up by the sun, it starts to evaporate — meaning tiny water particles jump from the water into the air. Evaporation is the word we use when liquid turns into gas. The tiny water particles get collected on the inside of the plastic bag because the bag is sealed, and after a while we can start to see water droplets forming. This is called condensation, the word we use when gas turns into liquid. When the droplets reach a certain size, they start to join together into bigger water drops and fall down in the water (just like rain). This process is called precipitation.