17 Sep STEM Challenge – How do Leaves Breathe?
You have been learning about living vs. non-living things! You know that trees, plants, and leaves are living things, and with this week’s STEM Challenge you will be able to see how plants “breathe.” We’re going to create an environment where we can actually SEE photosynthesis taking place — the oxygen/carbon dioxide process of plants!
Visit our blog every Thursday to see our latest STEM challenge and share your creations on social media using #CMMSSTEMChallenge or by emailing firstname.lastname@example.org. Be sure to submit your photos to us by Monday, September 21!
- Large Clear Bowl
- Lukewarm Water
- A Large “Active” Leaf
- A Sunny Spot
- Some Time!
- Fill a large bowl with lukewarm water. You can use a glass or plastic bowl – a see-through bowl is best.
- Head outside and find a large leaf. You’ll want to remove a leaf from a tree or plant and not just pick one up off the ground as we want an ‘active’ leaf for the project.
- Place the leaf in the bowl of water and put a small rock on top of it so it is FULLY submerged under the water. Then put the bowl in a sunny spot. If you have a place inside that’s super sunny, you can also try keeping the bowl there, otherwise you will need to keep it outside in the sun.
- WAIT! To see this experiment in action you will have to wait a few hours. Spend some time moving around and being active outside while you wait! Make a hypothesis – what do you think you will find when you look again after some time has passed?
- Take a peek a few hours later. What you should be seeing is small bubbles that form around the leaf and the edges of the bowl. These are easy to see with the naked eye but having a large magnifying glass could also be helpful.
Explaining Photosynthesis & Respiration in Plants and Trees
What would happen if you held your breath, went underwater in the pool, and then let your breath out? You would see bubbles coming up in the water.
That’s what you are seeing here — the leaf is still using the sunlight as part of the photosynthesis process (where leaves convert sunlight into energy).
As a leaf creates that energy, it needs to get rid of the items it no longer needs so it will let go of the extra oxygen during photosysthesis. The process of photosynthesis is what allows us to see the bubbles — as the leaf releases its’ extra oxygen while under water, the oxygen can be seen as bubbles in the water.
And since oxygen is lighter than water, the bubbles will eventually rise to the surface!