21 Mar DIY Science at Home: Water Cycle in a Bag
Source: KiwiCo.com
This popular STEM activity allows children to visualise the water cycle in real-time by creating a mini ecosystem in a plastic bag. When placed in a sunny window, the heat causes the water to evaporate, condense on the sides, and creates “precipitation” that runs back down into the bottom of the bag.
You will need:
- Zip lock plastic bag
- Water
- Blue food colouring
- Permanent Marker
- Tape (for hanging on the window)
Decorate the bag: Use your permanent marker to draw a sun at the top, some clouds, and then water/waves and the bottom.
Add labels: Label the stages – evaporation (near the top), condensation (clouds), precipitation (falling drops) and collection (water at the bottom).
Prepare the water: mix a few drops of food colouring into a cup of water then pour it into the bag.
Seal and Tape: carefully seal the bag and tape it to a sunny window. Tape it at a slight angle to simulate the run-off and collection stages of the cycle.
The science: Evaporation occurs when the sun heats the water, turning into water vapour (a gas). Condensation is the when the vapour cools at the top of the bag, changing back into liquid water droplets.
Precipitation occurs as the droplets get larger and heavier, they slide down the sides of the bag.
Collection is when the water flows back down, collecting at the bottom to repeat the cycle.
Check in on the water cycle in a bag at different times throughout the next few days and decide whether it mimics the water cycle we see on Earth. Good luck!
Sources (& more info):
https://littlebinsforlittlehands.com/water-cycle-in-a-bag/
Fun Science Demos: https://www.youtube.com/shorts/hBRR_7WagBU