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Activity Number 9 - An Experiment

Purpose

To show that water vapour enters the air though evaporation and transpiration.

Materials

  • Water
  • Saucer or shallow bowl
  • Tape
  • A healthy houseplant
  • Plastic bag

Method

Pour some water onto the saucer or shallow bowl. Next, mark the height of the water level with a piece of tape. Place the dish with the water in it on the windowsill for the day. Wrap the plant (pot and all) in the plastic bag and put it too on the windowsill for a few hours. What happened to the level of the water? What did your students notice about the plastic bag covering the plant?

Observations

The level of the water dropped down below the tape mark. Droplets of water appeared on the inside of the plastic bag containing the plant.

Conclusion

These are two ways in which water enters the atmosphere: evaporation and transpiration. Water evaporated from the dish into the air above it, changing from a liquid to a gas. The plant lost water through its leaves into the air, through a process call transpiration.

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