The title of this post is “how leaves breathe,” but leaves technically don’t “breathe.” Instead, leaves engage in processes called respiration and transpiration. This activity provides kids with a visual way of understanding the second process, that of transpiration.
A very brief description of transpiration is this: Leaves contain small pores called stomates. During the process of photosynthesis, where plants make their own food, leaves give off water through their stomates.
The activity I describe below provides a very visual way for kids to understand leaf transpiration as the giving off of water.
Note: For more leaf activities, see my Botany Unit Study page.
Background info to prepare for the leaf transpiration demonstration
I first introduced this activity by engaging my kids in a conversation about how we breathe. We used our hands to feel our breath coming out of our mouths. We also put our mouths right up to a mirror and breathed out, watching as a small patch of fog appeared on the mirror. We talked about how the patch of fog was made from water vapor, and that the water vapor had come from our lungs while we breathed.
I explained that people are constantly giving off water vapor (as well as carbon dioxide) when they breathe. And, as it turns out, trees do the same thing!
Performing the leaf transpiration demonstration
To demonstrate the fact that leaves give off water through transpiration, we grabbed two large and clear plastic bags.
We went into our backyard and placed the bags over two tree branches with plenty of leaves. XGirl placed her bag on the leaves of our orange tree.
QBoy placed his bag on the leaves of our maple tree.
We closed the bags as best we could around the leaves using the zip close seals (you could use tape if your bags don’t have a zip close top). Then we waited several days.
When we returned to the orange tree, we could see that a lot of condensation had built up inside the bag.
And a fair amount of water had collected at the bottom of the bag as well.
The maple tree had also given off some water, although much less than our orange tree.
The kids were super impressed at how much water we collected. And it was a very visual way to see that leaves give off water!
Fun fact #1: 90% of the water that trees take up from the ground is eventually released back into the air through transpiration.
Fun fact #2: Transpired water from leaves can be collected and consumed in a survival situation.
More resources for learning about leaves
More leaf posts from Gift of Curiosity:
- The best way to preserve leaves
- Leaf anatomy
- How leaves “breathe”: A transpiration demonstration
- How leaves get water
- How and why leaves change color in the fall
- Leaf collages art project
- Leaf rubbings activity book
- Fall leaves Sudoku
- Fall leaves lacing cards