Collecting Water Vapor

Collecting Water Vapor


  • clear plastic bags
  • masking tape

Background Information

Water used by plant leaves during photosynthesis passes, as water vapor, through openings on the surface of the leaf called stomata. This movement of water vapor is called transpiration. Water as a gas can’t be seen but when you stand under a tree on a hot day you know that transpiration is occurring. Air traveling across the water vapor is cooled so standing in a tree’s shadow is comfortable not only because of the sun cover but also because of the natural air conditioning.


Divide the children into groups of three. Each group should select a different tree and place a clear plastic bag over a branch with green leaves. They should then seal the bag with masking tape.

Ask the children to predict what will change after an hour’s time.

Write the predictions down to compare with the actual results.

After about an hour check the bags. They will have water in them. Compare the results with the predictions.

Ask the children to form a conclusion. How did the water get into the bag? Then explain transpiration.

Activity provided by:

Fontenelle Forest
1111 N. Bellevue Blvd.
Bellevue, NE 68005

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Category: Group Activities

Iowa Early Learning Standards:
8.2, 9.1, 9.2, 9.3, 9.4, 12.1, 12.4, 12.5